Rapid lace system DC's Rapid Lace System - DC's proprietary one string Rapid Lace System allows for easy micro adjustment of the boot's fit - both the upper and lower portions. Just pull up, pull back, and you're locked in. Command Liner The command liner is constructed from the inside out to provide you with optimized fit and comfort. The new support beam has been redesigned to be anatomically correct and deliver perfectly balanced zonal support. Out power straps have been included for liner closure and directional fiber lining has been integrated into the heel area for easy boot entry and heel hold down.