Coupler Pin, 1/2 Circle
Used to secure the slider-type collar on Bulldog couplers in a locked position when engaged on the trailer ball. The usable length inside the pin is 2 3/8". The actual pin diameter is 5/16".
This one was chosen specifically because of the "thumb tab" at the end, which makes it user friendly for people with arthritis or for children.
Fasten the coupler pin to the trailer with a lanyard & a #12 stainless steel screw, so the pin can't get lost. See below.