-Lock-In™ ReCap 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. -2 Different Size Caps Lock-In™ ReCaps and are available in two sizes, C-1 and C-2, to better match pad sizes lowering the pad\'s overall profile. Pro Derby C1=XS,S,M&L C2=XL Pro Knee C1=XS C2=S,M,L,XL Experience the difference.