Race Face – Ambush Knee Guard Open-back construction means no awkward shoe removal on the trail. Featuring D30(TM) high performance shock absorbing foam. D30(TM) high performance shock absorbing foam. Perforated Neoprene enhances venting and moisture control. Terry lined for wicking and comfort. Open-back construction; no shoe removal necessary. Foam padded side walls offer additional coverage. Branded rubber grab tabs.