The retractable QD-4 comes with a unique locking system that allows quick deployment and a positive lock. Extend it to the desired length and it is ready to use. The minimum extension is 31 ½" for pediatrics, and the maximum extension is 54 ¾" for adults. Features include a low profile "Hare-Type" ischial pad, 4" x 3" wide adjustment elastic straps, and an integral folding heel rest. The ankle hitch is impregnated with antibacterial, antimicrobial Staphcheck materials.