G-Form Youth Pro-X3 Knee Guard Matte Black LXL PairG Form Pro X3 Youth Knee Guards Black Large X Large. The G Form Pro X3 Youth Knee Guards provide comfortable and lightweight protection. Designed for trail all mountain and cross country riding these knee guards feature G Forms SmartFlex pad technology. SmartFlex pads offer form fitting and lightweight protection that is flexible as you ride and hardens on impact Body mapped impact absorbing SmartFlex pads layered on top of a ventilated soft inner