Bulldog 580402 Dogbone Coupler Lock 5/8 In Stainless
Bulldog 580402 Dogbone Coupler Lock 5/8 In Stainless — Product description
The Bulldog 580402 is a stainless steel dogbone coupler lock with a 5/8 inch keyed pin and a dust cap. It fits couplers rated for Class III and IV hitches, blocking the latch so nobody lifts your trailer off the ball or drops it onto theirs. Cheap insurance at the ramp or in storage.
If you tow a boat, you already know the coupler is the weak point. Back down the ramp, drop the boat in, and your empty trailer sits in the lot with nothing stopping someone from lifting the coupler onto their own ball and driving off. That's exactly what the Bulldog 580402 is built to stop.
This is a dogbone-style coupler lock made from stainless steel, with a 5/8 inch diameter pin and a keyed cylinder. It fits couplers rated for Class III and IV hitches, which covers most boat, utility, and equipment trailers. Slip it through the coupler, turn the key, and the latch can't be opened and the coupler can't be dropped onto a ball. Simple, and it works.
Stainless steel matters more than folks think. A trailer lock lives outside. It rides through rain, road salt in the winter, and saltwater spray every time you launch. A plated lock rusts, the keyway seizes, and one day you're standing at the ramp with a key that won't turn. Stainless holds up to all of that. The included dust cap covers the keyway when the lock isn't in use, so grit and salt stay out of the cylinder.
We like this one for the boat that lives on the trailer year-round, parked in the driveway or a storage lot between trips. It's also cheap insurance at the ramp when you're out on the water for a few hours and the trailer is sitting unattended. Will it stop a determined thief with an angle grinder? No lock this size will. But it stops the grab-and-go theft that accounts for most stolen trailers, and that's the whole point.
Keep the key on your boat keyring and you'll always have it when you need it. And because it's Bulldog, you're getting gear from a name that's been building couplers, jacks, and hitches for the towing trade for a long time.
Key Features
- 5/8 inch diameter locking pin puts a solid, hard-to-cut bar across the coupler latch
- Stainless steel construction shrugs off rain, road salt, and saltwater spray at the ramp
- Keyed cylinder lock, no combinations to forget
- Included dust cap keeps grit and salt out of the keyway between trips
- Fits couplers rated for Class III and IV hitches, covering most boat and utility trailers
- Dogbone design blocks the latch so the coupler can't be lifted off or dropped onto a ball
Why Buy from NVN Marine
- Authorized Bulldog reseller, full manufacturer warranty
- NMEA member and ABYC certified, advice from real boat techs
- Same-day shipping before 3 PM ET on in-stock items
- NY headquarters and Fort Lauderdale flagship retail store
Technical specifications
| Title | Bulldog 580402 Stainless Steel Dogbone Coupler Lock |
|---|---|
| Brand | Bulldog |
| Manufacturer Part Number | 580402 |
| UPC | 783192025807 |
| Hitch Compatibility | Class III / IV |
| Lock Style | Dogbone |
| Pin Diameter | 5/8 inch |
| Material | Stainless Steel |
| Lock Type | Keyed |
| Dust Cap | Included |
Frequently asked questions
What size is the locking pin?
It's a 5/8 inch diameter pin, which is the standard size that fits the latch opening on most Class III and IV trailer couplers.
What hitches does this lock fit?
It's designed for couplers rated for Class III and IV hitches. That covers the vast majority of boat, utility, and equipment trailers.
Is it actually stainless steel?
Yes. The whole lock is stainless steel, so it resists the rust and corrosion that seize up plated locks after a season of rain and saltwater.
Does it come with a dust cap?
It does. The dust cap covers the keyway when the lock isn't in use, keeping road grit and salt out of the cylinder so the key still turns when you need it.
How does it keep my trailer from being stolen?
The keyed lock blocks the coupler latch, so a thief can't open the coupler to lift it off your ball or drop it onto theirs. It stops the quick grab-and-go theft that most trailers fall to.
Can I leave it on the trailer in the weather?
Yes. Between the stainless steel body and the dust cap over the keyway, it's built to live outside through rain, snow, and salt.
