Weather Guard 121-52-03 aluminum crossover saddle truck tool box in matte black, front three-quarter studio view

Weather Guard 121-52-03 aluminum crossover saddle truck tool box in matte black, weather-seal and lid edge detail

Weather Guard 121-52-03 aluminum crossover saddle truck tool box in matte black, tie-down buckle detail

Weather Guard 121-52-03 aluminum crossover saddle truck tool box in matte black, gas strut and reinforced lid detail

Weather Guard 121 Aluminum Crossover Truck Tool Box, Full-Size Low-Profile, Matte Black (121-52-03)

Brand: Weather Guard FREE Shipping Low Stock

$1,099.00

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The Weather Guard 121-52-03 is the previous-generation full-size low-profile aluminum saddle box, offered here as the proven, value-priced version that came before the current 1Key UltraLock update. Security comes from the One Key push-button high-security lock, which codes multiple boxes on a truck or a whole fleet to one key and stays PowerSync capable for Weather Guard interior lights and remote keyless entry add-ons. The five-piece welded aluminum diamond-plate body wears a textured matte black ARMOR TUF finish that kills glare and hides fingerprints, dust and light scratches for a clean, understated truck. Its low-profile lid line sits lower across the bed for better rear visibility while still delivering 10.2ft³ of weather-sealed storage over the top bed rails behind the cab. A reinforced lid on gas struts and a full-perimeter D-shaped weather seal keep rain and grit out load after load.

What's Included:

121 Series full-size low-profile aluminum crossover (saddle) tool box in matte black
One Key push-button high-security lock, keyed alike
Under-rail mounting clamps and hardware for a no-drill install
Gas struts with welded strut shields
Removable divider tray
Full-perimeter D-shaped weather seal, pre-installed
Weather Guard installation instructions

Features

Welded Aluminum Diamond-Plate Build
A five-piece welded aluminum diamond-plate body with a reinforced C-channel front panel keeps this box strong yet light. It resists jobsite abuse and road salt without adding the weight of a steel box. This one is finished in textured matte black ARMOR TUF powder coat.

Textured Matte Black ARMOR TUF Finish
Textured matte black ARMOR TUF powder coat throws off almost no glare and swallows fingerprints, dust and small scuffs that a glossy coat would show. It gives the box a tactical, understated look and wipes down fast between jobs.

One Key Push-Button High-Security Lock
This redesigned saddle box uses a push-button high-security lock that codes multiple boxes on a truck or fleet to one key, and it is PowerSync capable for Weather Guard interior lights and remote keyless entry accessories.

Full-Perimeter Weather Seal
A memory-resistant D-shaped, multi-ridge weather strip runs the entire lid perimeter to keep rain, dust and debris off your tools, so your gear stays dry and ready in any weather.

Reinforced Lid With Gas Struts
Gas struts hold the reinforced lid open near 90 degrees for easy one-handed access, and welded strut shields protect them from damage. The steel-reinforced lid resists flex and stands up to daily use.

Saddle Fit Across The Bed
By straddling the two bed rails behind the cab, the box leaves the bed floor wide open for plywood, ladders and long cargo. Enhanced tie-down buckles anchor loose loads and a 12V PowerSync-ready port supports interior lighting and electrical upfits.

Fitment & Compatibility

Truck Class	Example Trucks	Fit
Full-size 1/2-ton	F-150, Silverado/Sierra 1500, Ram 1500, Tundra, Titan	✓ Yes, spans the top bed rails behind the cab
Full-size 3/4-ton and 1-ton	F-250/F-350, Silverado/Sierra 2500/3500, Ram 2500/3500	✓ Yes, ideal application
Mid-size and compact	Ranger, Colorado, Tacoma, Frontier, Maverick	✗ No, not designed for smaller beds

Fit guidance: Crossover, or saddle, boxes mount across the truck bed on top of the two bed rails just behind the cab, so the box straddles the bed and leaves the bed floor open. At about 72" wide this size fits standard-width full-size pickups, and because it sits on the rails rather than the bed floor it works with short, standard and long beds on those trucks. Always measure your bed rail width and check clearance behind the cab before ordering. It is not designed for compact or mid-size trucks.

Specifications

Series: 121 Series Aluminum Crossover (Saddle)
Style: Full-Size Low-Profile, single-lid saddle/crossover
Storage Capacity: 10.2ft³
Exterior Dimensions: 72"L x 20"W x 18"H
Material: Aluminum diamond plate, five-piece welded body, C-channel reinforced front
Finish: Textured Matte Black ARMOR TUF
Lid: Reinforced, opens near 90 degrees, gas struts with welded strut shields
Lock: One Key push-button high-security lock, PowerSync capable
Weather Seal: Full-perimeter D-shaped, multi-ridge weather strip
Mounting: Under-rail clamps and hardware included, no drilling required
Electrical: 12V PowerSync compatible access
Weight: About 79 lb (shipping weight)
Warranty: Limited Lifetime
Made In: USA

Installation

Type: Saddle mount across the top bed rails, clamp-in with no drilling · Time: About 20 to 30 minutes · Tools: Socket or wrench set and a tape measure; no drill needed with the included under-rail clamps · Difficulty: Easy, best done with two people for the lift

Set the box across the two bed rails behind the cab and center it left to right. Hook the included clamps under each bed rail and tighten the hardware evenly so the box sits flat and the lid seals all the way around. Because the box is wide, have a second person help lift and hold it while you clamp it down. Follow the Weather Guard installation instructions for exact clamp placement and torque.

Watch the installation walkthrough:

Resources

Everything you need for your Weather Guard 121 Aluminum Crossover Truck Tool Box, Full-Size Low-Profile, Matte Black, in one place.

Official Weather Guard 121 Aluminum Crossover Truck Tool Box, Full-Size Low-Profile, Matte Black installation manual (PDF), the manufacturer's step-by-step guide covering mounting, included hardware and torque specs.

Warranty, Shipping & Returns

Warranty. Limited Lifetime Warranty from Weather Guard against defects in materials and workmanship.

Free shipping. This item ships free to the lower 48 states. Because it is an oversized item, it ships by freight and typically arrives in 3 to 7 business days.

Inspect on delivery. Please inspect the packaging before signing. If you see any damage, note it on the delivery receipt and contact us right away, and we will make it right.

About Weather Guard

Weather Guard has built professional-grade truck and van storage in the USA for decades and is the storage brand tradespeople, contractors, and fleets reach for first. Its steel and aluminum tool boxes, ladder racks, and van-interior systems are engineered to survive daily jobsite abuse and keep expensive tools secure and organized.

Known for weather-tight seals, patented locking systems, and heavy-gauge construction, Weather Guard products mount cleanly on work trucks and vans and stand up to years of hard use. The lineup spans crossover, low-side, and saddle truck boxes, ladder and van racks, drawer units, and fuel and utility tanks, so an entire work vehicle can be outfitted from one brand.

Backed by a strong manufacturer warranty and US-based support, Weather Guard is the name pros trust to protect the tools their livelihood depends on.

Authorized Weather Guard dealer. Prestige Truck is an authorized dealer of Weather Guard, so every tool box, rack and storage product you buy is 100% genuine and factory-new, covered by the full Weather Guard manufacturer warranty, and backed by our own US-based support team.

Compare The Range

How this compares to similar models

The closest alternatives side by side, so you do not have to keep tabs open.

Model	This OneWeather Guard 121 Aluminum Crossover Truck Tool Box, Full-Size Low-Profile, Matte Black (121-52-03)	DECKED Tool Box, Full-Size Truck Crossbed, 71.7" x 25.5" x 16", 300 lb Lid / 800 lb Tub, Black (DTB2-BLK)	Weather Guard 126 Steel Crossover Truck Tool Box, Full-Size Standard, Brite White (126-3-03)	UWS 69" Deep Push Button Crossover Truck Tool Box, Matte Black Aluminum (TBSD-69-PB-MB)
Price	$1,099.00	$1,099.99	$1,099.00	$1,099.95
Style	Truck Tool Box	Truck Tool Box	Truck Tool Box	Truck Tool Box
Series	121 Series Aluminum Crossover (Saddle)	—	126 Series Steel Crossover (Saddle)	—
Style	Full-Size Low-Profile, single-lid saddle/crossover	—	Full-Size Standard, single-lid saddle/crossover	—
Storage Capacity	10.2ft³	—	10.6ft³	—
Exterior Dimensions	72"L x 20"W x 18"H	—	72"L x 20"W x 18"H	—
Material	Aluminum diamond plate, five-piece welded body, C-channel reinforced front	—	Heavy-duty formed steel, reinforced lid and front	Aluminum, 0.058" one-piece tub
Finish	Textured Matte Black ARMOR TUF	—	Brite White ARMOR TUF	Matte black powder coat
Rating	No reviews yet	40 reviews	No reviews yet	No reviews yet
Ships in	1 to 2 business days	1 to 2 business days	1 to 2 business days	1 to 2 business days
Action	You Are Here	View	View	View

Weather Guard Truck Box Hardware Installation Guide

Weather Guard's official hardware video zooms in on the clamp and bolt kit that secures its truck boxes to the bed rails without drilling. It is a helpful close-up companion to the full box install and shows how the mounting brackets hook under the rail lip and tighten down. Use it alongside the printed instructions that ship with the box.

Weather Guard Truck Box Lineup and 1Key UltraLock

This official Weather Guard overview tours the current truck box lineup and the 1Key UltraLock security system that runs across it. You see how one coded key can open every Weather Guard box on the truck, from saddle to lo-side to hi-side, with a pop-up red button that tells you at a glance whether a box is locked. It highlights the sloped, reinforced lids and the ARMOR TUF powder coat that let these boxes shrug off weather and jobsite abuse. If you run more than one box, or a whole fleet, it shows why keying everything alike saves time every day.

How to Replace the Lid on a Saddle Truck Box

Weather Guard's step-by-step guide to taking the lid off a saddle truck box and fitting a replacement. It covers the hinge and strut hardware that carries the lid, which is the part that takes the abuse on a box that gets opened twenty times a day. Keep it bookmarked rather than watching it now. It is the reference you want the day a lid gets damaged on the job, and it comes straight from the manufacturer so the hardware and the sequence are correct.

Frequently Asked Questions

Straight answers on specs, fit and support

Will the 121-52-03 fit my truck?

It is a full-size low-profile crossover, or saddle, box that mounts across the top bed rails behind the cab, so it fits full-size pickups such as the F-150, Silverado and Sierra 1500 through 3500, Ram 1500 through 3500, Tundra and Titan. It needs about 72" of rail-to-rail width. Measure your bed rails and check clearance behind the cab first, and note it is not designed for compact or mid-size trucks.

Does it require drilling to install?

No. The box ships with under-rail clamps and hardware, so it mounts without drilling into your truck. Most installs take about 20 to 30 minutes and go easiest with two people to lift and hold the box while you clamp it down.

How does the lock on this saddle box work?

This earlier-generation saddle box uses a One Key push-button high-security lock. Press the button to release the lid, and the keyed cylinder lets you code several boxes on one truck, or an entire fleet, to a single key. It is PowerSync capable as well, so it pairs with Weather Guard interior lights and remote keyless entry accessories.

Will the matte black finish fade or stain in the weather?

No. The textured matte black ARMOR TUF coat is built to shrug off UV fading and corrosion, and the full-perimeter D-shaped seal keeps rain and dust off the contents. Its flat, low-sheen texture also does a good job hiding water spots and road film between washes.

Is this an earlier-generation box, and why does it cost less than the current model?

Yes. This is the previous-generation 121 low-profile saddle box, built around the proven One Key push-button high-security lock and PowerSync wiring instead of the newer 1Key UltraLock hardware on the current version. The welded aluminum diamond-plate body, low-profile lid line, weather seal and no-drill mounting are the same design, so you get the same day-to-day performance at a value price.

What is it made of and how big is it?

This previous-generation low-profile box is five-piece welded aluminum diamond plate under a textured matte black ARMOR TUF coat. It measures 72"L x 20"W x 18"H, holds 10.2ft³, and ships at about 79.05 lb, so it is light, low and value priced.