Amazon.com: YITAMOTOR 4-Inch Hitch Receiver Pin Lock with 5/8" Diameter, Extra Long Stainless Steel Trailer Hitch Locking Pin, Fits Class III IV 2" & 2-1/2" Receiver, Silver : Automotive
Amazon.com: Double HH 2 Pack X Square Wire Lock Pin, 5/16" by 2-1/4" : Automotive
4 Pcs Tiny Safety Coupler Pin 3/16" x 1.97"(4.8mm x 50mm), Full Marine Grade 316 Stainless Steel Shaft Locking Pin, Small Pins Please Check The Size First: Amazon.com: Industrial & Scientific
Large Square Safety Coupler Pin 1/2" x 3-1/2"(12.6mm x 90mm), Full Marine Grade 316 Stainless Steel Heavy Duty Shaft Locking Pin: Amazon.com: Industrial & Scientific