The Joint VPD System Knee is a highly flexible, 2-ply knee protector which conforms with international shock absorption standards. The knee protector features a highly efficient ventilation system and an outer fabric which is made with high-tenacity polyamide yarns for low friction and high abrasion resistance. VPD is the perfect material for mountain biking as it wraps around a rider’s body shape when warm, which gives great freedom of movement on a bike. To protect riders during a fall, the VPD technology then hardens on impact to help minimize injury.