These files are set up blocks for the Defu 368A key machine to hold the key up higher in the clamping block so the cutting bit does not hit the steel clamping block. you will need two of these one for the sample key and one for the key being cut. Place them in the bottom of the slot and place the key blade on top. There is a 1mm thick x 30mm long x 5mm wide and a 1.2 mm thick x 30mm long x 5mm wide version.