When sourcing knee pads, prioritize high-density EVA foam for impact absorption and ballistic nylon (1200D or higher) for the outer shell to ensure abrasion resistance. The hard caps (shells) should be made of high-impact polyethylene (PE) or polypropylene (PP), secured with reinforced rivets. For professional vert or downhill skating, look for 'butterfly' closure systems that allow for easy on/off without removing shoes, and contoured designs that maintain the pad's position during high-velocity slides.