This is the coupler that goes on the trailer, the part that drops over the gooseneck ball in your truck bed, and B&W rebuilt it around two ideas. The first is that hooking up should take one movement: line the ball up, lower the trailer, and the automatic latch closes, with a cone-shaped mouth doing the fine alignment so you are not shuffling the truck back and forth for the last inch. The second is that a gooseneck trailer parked anywhere is currently a trailer anyone with a truck can take. The Defender has a push-button keyed lock built into the coupler, and it locks whether the trailer is coupled to your truck or standing on its own, so you can secure a trailer at a jobsite, at a campground or on your own driveway without hanging a separate coupler lock on it and hoping. Rated 25,000 lb gross trailer weight and 7,500 lb vertical tow weight with its 2-5/16" ball socket. It fits standard gooseneck trailer tubing and is a replacement for the coupler your trailer came with, so it is a trailer modification rather than a truck accessory.
What's Included:
B&W Defender locking gooseneck coupler
Keys for the integrated push-button lock
Installation instructions
Features
The Lock Is Part of the Coupler A push-button keyed lock is built into the body rather than hung off it. That matters because an add-on coupler lock is a visible, attackable object; an integrated lock has nothing to cut off. It works coupled or uncoupled, so the trailer is secured on your ball and secured sitting on its jack.
Automatic Latch Line up the ball, lower the trailer, and you are latched. There is no lever to throw and no sequence to remember, which removes the failure mode where somebody hooks up in the dark, thinks it is latched and finds out at the first turn.
A Cone That Does the Aiming The mouth of the coupler is cone shaped, so it guides itself onto the ball from an imperfect position. Anyone who has backed a gooseneck alone on gravel understands what that is worth.
25,000 lb GTW and 7,500 lb VTW Those are this coupler's ratings on its 2-5/16" socket. Your truck's gooseneck rating, your trailer's own rating and the ball in the bed all carry their own numbers, and the lowest of them governs what you can legally and safely tow.
A Theft Deterrent You Will Actually Use Security that takes effort gets skipped. This one is a button and a key at the point you are already standing, which is the difference between a trailer that gets locked every time and a chain in the toolbox that never comes out.
Fitment & Compatibility
What It Fits
Detail
Mounts on
● The trailer, replacing the existing gooseneck coupler
Ball size
● 2-5/16" gooseneck ball
Gross trailer weight
● Up to 25,000 lb
Vertical tow weight
● Up to 7,500 lb
Truck year, make and model
✗ Not a factor; this is a trailer part
Fit guidance: This is a trailer part, not a truck part, so there is no year, make and model list. What it has to match is your trailer's gooseneck tube and your truck's ball: it is built for a 2-5/16" ball, which is the common heavy gooseneck size. Fitting it means replacing the coupler currently on your trailer, so measure your gooseneck tube and read B&W's installation instructions before ordering. If your trailer is a fifth wheel rather than a gooseneck, this is not the product; B&W's fifth wheel to gooseneck adapters are what convert that.
Specifications
B&W Part Number: GNC4250
What It Is: Locking gooseneck coupler, mounts on the trailer
Ball Size: 2-5/16"
Gross Trailer Weight: 25,000 lb
Vertical Tow Weight: 7,500 lb
Lock: Integrated push-button keyed lock, works coupled or uncoupled
Latch: Automatic, closes when the trailer is lowered onto the ball
Coupler Mouth: Cone shaped, self-aligning
Finish: Black
Shipping Weight: About 42 lb
UPC: 843233002355
Warranty: B&W Lifetime Exclusive Limited Warranty
Made In: Made in the USA, built by B&W in Humboldt, Kansas
Installation
Type: Replaces the existing coupler on the trailer's gooseneck tube · Time: Allow a couple of hours · Tools: Depends on how the existing coupler is attached; welding may be involved · Difficulty: Intermediate to advanced, and it is a structural part of the trailer
This is the part your trailer hangs from, so it is not a job to improvise. Support the gooseneck properly before removing the old coupler, follow B&W's instructions for this part number exactly, and if the installation calls for welding, have it done by someone who welds for a living. Test the latch and the lock with the trailer empty before you load it.
Resources
Everything you need for your B&W Defender Locking Gooseneck Coupler, 2-5/16", 25,000 lb GTW, Keyed Lock, Black, in one place.
Warranty. B&W covers this product with its Lifetime Exclusive Limited Warranty. B&W warrants its products to the original consumer purchaser, for as long as that purchaser owns the product, against defects in material and workmanship. The remedy is replacement, or repair or a full refund at B&W's option. Installation and removal labor, shipping costs, and damage caused by misuse, overloading, alteration or improper installation are not covered. Warranty service goes directly through B&W at 800-248-6564, which issues a return authorization before anything is sent back. B&W states that it does not authorize dealers or distributors to create any other warranty, so what is described here is B&W's own coverage and nothing has been added to it.
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 B&W Trailer Hitches
B&W Trailer Hitches started in 1987 in a Humboldt, Kansas garage, where Roger Baker and Joe Works built the first Turnoverball gooseneck hitch. The idea was simple and nobody else had done it: a gooseneck ball that turns over and stores flush with the bed floor, so the truck bed goes back to being a truck bed the moment you unhook. That one product built the company, and B&W still makes its hitches in Humboldt, in a plant that has grown to about 600,000ft². The company has been 100% employee-owned since 2007, with roughly 500 employee-owners who have a stake in what comes off the line.
The testing story is worth knowing, because it is not how the rest of the industry does it. SAE J-2638, the standard for gooseneck and fifth-wheel hitches, is a recommended practice, and it is common to satisfy it with a fresh sample for each test. B&W runs a single hitch through all three 300,000-cycle dynamic tests and the six static tests, one after another, on the same unit. The Tow & Stow line is tested to SAE J-684. Every B&W-brand product is covered by the company's Lifetime Exclusive Limited Warranty to the original consumer, against defects in material and workmanship, for as long as that person owns it.
Prestige Truck is an authorized B&W dealer. Every B&W product we ship is new, in the factory carton, and backed by B&W's own warranty and its US-based support team in Humboldt, Kansas.
The Defender Locking Coupler In Use
A second B&W video on the Defender, covering the locking and unlocking sequence and how the coupler behaves when it is left locked on the ball.
Useful for seeing the key and button working at real speed rather than in a studio.
The Robot Weld
A close look at the robotic welding cells that lay down the structural welds on B&W hitches, and the people who program and check them.
Consistent welds are what capacity ratings depend on, and this is how B&W makes sure every weld is the same as the one that passed the test lab.
Set Your Mirrors For Towing
B&W's quick guide to setting truck mirrors for a trailer: what you need to see, where the blind spots move, and when extended mirrors earn their keep.
A thirty-second adjustment before you pull out makes every mile after it safer.
Frequently Asked Questions
Straight answers on specs, fit and support
Does this go on my truck or on my trailer?
On the trailer. It is a coupler, which is the part that drops over the gooseneck ball, so it replaces the coupler your trailer came with. The ball in your truck bed stays as it is, as long as it is a 2-5/16".
What is it rated for?
25,000 lb gross trailer weight and 7,500 lb vertical tow weight. Those are this coupler's figures on its 2-5/16" socket. Your truck, your trailer and the ball in the bed all carry ratings too, and the lowest of them is the one that governs what you can tow.
Can I lock the trailer while it is hitched to my truck?
Yes, and that is one of the reasons for the design. The integrated push-button keyed lock works both coupled and uncoupled, so you can secure the trailer to your ball, or secure it standing on its jack at a jobsite or campground.
Is a locking coupler really worth it?
It depends what the trailer is worth to you and where it sits. An unlocked gooseneck parked anywhere is a trailer that anyone with a truck and a ball can back under and drive off with. The Defender makes that a locked-door problem rather than an open-door one, and because the lock is a button at the point you are already standing, it actually gets used.
Do I need to weld it on?
That depends on how your trailer's existing coupler is attached; some are bolted and some are welded. Read B&W's installation instructions for this part number before you start. This is a structural part of the trailer, so if welding is involved, have someone who welds professionally do it.
How does the automatic latch work?
Line the ball up, lower the trailer onto it, and the latch closes itself. The cone-shaped mouth does the last of the alignment for you. There is no lever to throw, which removes the most common hookup mistake, but you should still check visually that it is latched before you pull away, as with any coupler.
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