Carpet Knee Kicker features a five-setting length-adjustment channel that extends length from 17 1/2" to 21 1/2", operated by a recessed trigger that locks in each position. The head grips carpet with the combined hold of three replaceable nap grippers and 16 adjustable steel pins. The pin dial gives a visual reference of pin length. Pins are protected in storage by the cap cover. The replaceable square bumper is foam-filled and covered by a tough, seamless, neoprene cover.