If your car mats have a life of their own and ride around the car, this should have stopped a long time ago. For this case there are special clips that fix the mat to the floor. This set comes with 4 clips, and while it is recommended to put only two clips on the mat, you will still have a reserve. The outer diameter is 41 mm and the inner diameter is 11 mm. Many cars have these clips on the floor mats from the factory, but if you don't have them, why not buy them.