Allen Sports Stainless Steel Locking Hitch Pin for Allen Hitch Mount Bike Racks (2-Inch Receiver) Stainless steel locking hitch pin locks and tightens Allen 2" receiver Racks (works with models 530RR, 540RR, 550RR, 640RR, and 740RR) Solid brass locking cylinder and cylinder case. Internal "O" ring and water-tight cap protect locking mechanism. Includes 3 keys. Lifetime on workmanship and material