Heininger 6001 Advantage SportsRack 2" Threaded Receiver Trailer Hitch Lock Threaded 5/8" diameter pin (11 threads) Hitch lock has a 0.625" diameter and works for all 2" receivers. For class III or class IV receivers. Anti-Theft lock with 2 Keys provided, Weather resistant locking head Compatible with TruckStep XL (#4037), Truck Twistep (#3045), Hitch Extension (#6000), and TiltAWAY (#3010) DOES NOT WORK WITH SUV TWISTEP #3052