FLY Racing Barricade Lite Adult Knee GuardsFly Racing Barricade Lite Knee Guards. FLY Racings HDM (High Density Memory) protectors are made of a special blend viscoelastic foam with memory function allowing for repeat impacts that passes CE EN1621 1 rating to level 1 Hidden stitching prevents fraying and adds to durability The protective pads feature an array of breathe holes to increase airflow Extended upper cuffs and internal silicon gripper bands help with slipping The pads are both soft,