This wheel cover is equipped with an adjustable retention ring. Patented adjustable retention ring with double groove/notch design assures for a secure fit. This ring can be placed in upper or lower notch located on each of the ring supports. This will increase tension to the proper level to ensure the best fit of the wheel cover. Use the upper groove for standard sized wheels, and use the lower groove to increase tension for bigger sized wheels. To put this trendy new wheel cover onto your wheel is just minutes away. No need of technician skills. Everything is "clip-on". This wheel cover has a very special matte black finish that gives your wheel a more fancy look and is very eye catching. This product is rust-resistant, easy to clean and also resistant to temperature extreme and corrosion. 4 single pieces are nest packed as 1 set with ring off. A brown carton is used as transportation box for shipping. BEFORE YOU MAKE A PURCHASE DECISION, PLEASE READ THE SIDE WALL OF YOUR TIRE TO FIND YOUR RIM SIZE WHICH SHOULD BE THE SAME WITH THE SIZE OF THE WHEEL COVER. FOR EXAMPLE, IF YOUR TIRE READS "R16", THEN YOU HAVE A 16" RIM SIZE. AND 16" WHEEL COVERS WILL BE FIT ON YOUR VEHICLE.