★With the correct holes, countersunk screws sit flush to the surface they are attached on, for less chance of catching on the track surface, etc. and causing damage or loss of speed. ★This set includes ten each of 6mm, 8mm and 15mm screws crafted in stainless steel. Compatible Cars Mini 4WD & Mini 4WD PRO cars *Item 74130 Electric Router Countersink Bit (for 2mm Screws) is recommended when making countersunk holes.