Change the filter or adapter or lens or other size from 40.5mm to 67mm..Transform caliber adapter ring, can be mounted to the front of the lens to achieve different diameter share the same lens diameter filter, lens hood, additional lens and other accessories. The purpose is to increase the diameter of the lens..To the side of the lens:40.5mm.To the side of the filter thread:67mm.【Note】Why Choose AMOPOFO Brand Concept？ professional camera accessory manufacturer. Dedicated to provide products in high quality & good price. Made of metal sealing ring, much tighter. Laser fonts, much durable.Meet Environmental Standards of RoHS.