The RevoRing allows you to attach one screw-in filter and apply it to multiple lenses without the need for step-up rings Each RevoRing features unique self retracting blade technology with threaded ends to secure on the front of your lens Each threaded end has been designed to overlap therefore completely removing any possibility of light leak All RevoRing products are made using Architectural grade Aluminum, keeping it lightweight and tough. The anodised finish also protects the ring from corrosion when shooting outside in unpredicted elements There are 5 variable size options to choose from