Snap Link, or Carabiner, 3/8" OD X 3 1/2" L (medium)
This medium size snap link is 3/8" in diameter, 3 1/2" in length & rated at 425lbs. Also known as a spring link. Electro-polished steel. This snap is what we recommend to securely fasten the Break-Away Switch Cable to the tow vehicle, because it has a large (1/2") opening & it's easier to find a place to fasten it to.
Wikipedia: A carabiner is a metal loop with a spring-loaded gate used to quickly and reversibly connect components, most notably in safety-critical systems.
Trail Pals Tip: Please take a good look at to the rear of your tow vehicle. After the safety chains are crossed & clipped to the tow vehicle, attach the break-away switch cable with this snap SEPARATELY, and clear from the chains. The other end of the 44" cable is attached to a pin inserted into the breakaway switch which is designed to pull out if the trailer loses it's connection with the tow vehicle. Pulling the pin out of the switch activates the brakes on the trailer (it stops the trailer so that it cannot move independently with the animals in it). Make sure the cable can't touch the ground, or it may fray. Slip the loop at the end of the cable onto this snap link and fasten it to the tow vehicle where there is a place to snap it into, or in the same hole as the safety chain clip---but clipped on separately. The cable must be capable of pulling the pin easily & completely out of the switch should the tow vehicle become detached from the trailer.