This is a cubic ring with a top wave surface and hollowed by rectangle array. You can check it in P3D "http://p3d.in/15w8Q". The default diameter is 17mm, if you need a customized diameter, please send me the message about your ring diameter or circumference. I will customize your ring and make it available in my shop with name of ring size. Please understand the hand-finishing won't reach the bottom, and micro inside surfaces.