D1- the diameter of the hole in the alloy wheel. Outside Diameter of the Hub Centric Ring / O'Ring / Spigot Ring (the diameter of the hole in the alloy wheel where you will insert the Hub Centric Rings / O'Rings / Spigot Rings)
D2 - the diameter of the center bore size of vehicle hub. Inside Diameter of the Hub Centric Ring / O'Ring / Spigot Ring (the diameter of the hub on which car you wish to use the Hub Centric Rings / O'Rings / Spigot Rings)
The Spigot Rings are made from Polycarbonate (PC) Plastics Polycarbonate plastics are among the strongest, toughest, and most rigid thermoplastics. They are resistant to a variety of chemicals. The creep resistance of these plastic materials is among the best for thermoplastics.
Pictures Used are for illustration purposes! you will receive different colors rings.