Feature:1. Sapphire watch glass material has good high temperature resistance and good heat conduction, and has higher hardness than ordinary glass.2. Each piece of glass has a highly clear and glossy edge treatment, no scratches and high gloss.3. These sapphire watch glasses are easy to install and use, and are useful watch parts and repair tools.4. The kit contains 5 pieces of 20-22mm glass, suitable for different watches and meet your different needs.5. These glasses are of moderate thickness and standard size, and can be accurately mounted on the watch.Specification:Item Type: Sapphire Watch GlassSpecifications: Approx.20mm / 0.79in20.5mm / 0.81in21mm / 0.83in21.5mm / 0.85in22mm / 0.87inIntermediate Thickness: Approx. 2.2mm / 0.09inEdge Thickness: Approx. 1.7mm / 0.07inDiameter Error: Approx. ±0.2mm / 0.01in Package List:5 x Sapphire Watch Glass