Fastway ONEstep Wheel Chock Double Pack For Tandem Axle Trailers and RVs 84-00-4840 --16 Inches to 24 Inches Long -- QTY 2 The highest amount of stability and security available. Keeps your trailer from rocking. More comfortable set-up: sets and removes from a standing position, no more kneeling down. Keeps your trailer firmly locked in place, reducing movement when you are in the trailer. No more hunting around for heavy rocks when you get to your camping spot. Prevents your trailer from rocking and rolling when parked.