Easy to install and remove, Lock In™ ReCaps are designed to fit the Pro Knee Pad and Pro Derby Pad. With minimal spacing between the cap and the pad, they are made of specially formulated materials they are durable and long lasting. Created specifically for the Pro Knee and Pro Derby pads. The new advanced Lock-In™ ReCap System closely contours the foam core and pad casing, greatly minimizing gaps between cap and pad. The new design sets a lower profile allowing for less bulk and optimum performance. Lock-In™ ReCap System. - A loop found on interior of the cap works with the strap on the front of the pad to securely hold and align cap in correct position. Side strips of velcro provide additional stick. 3 Different Size Caps - Lock-In™ ReCaps and are available in three sizes, C-1, C-2, and C3 to better match pad sizes lowering the pad's overall profile.