Sharp End Covers For BAK Industries X4S Tonneau Cover.  Custom made covers to fit over the sharp rail ends of the BAK Industries X4S and X2 Tonneau Cover. These covers were 3-D printed with flexible TPU (Thermoplastic Polyurethane) filament to tightly fit over the sharp end. Includes two covers, a left and a right.  Most rails have a width of 1 & 7/8".  If you have a Ram truck with the Ram Box the rails are @ 2 & 1/8" wide, so send a message before your order if you need the "Ram Box" rail covers.