Carbon fiber frames + concrete + bitumen don't mix very well. We designed some light weight sacrificial body armour to protect your gear. So if you are a ghetto racer, bang these on and fly harder longer. Se instructions for more info.The arm rails are for front strikes and also for a rolling tumble. The bottom bumpers are just for end on strikes. For underside protection, see our landing skids. The cut out section on the rear bottom is for the battery cable exiting from between the plates. Otherwise the front bumper fits just fine. We recommend hot glue for a semi-permanent fix. The top and bottom plates can be fixed with M3 screws. Otherwise a couple of zip ties should do the trick.