This plastic insert is a part of the complete Lens Ring V2. You will only need it if you are building your own or upgrading your lens ring. You will also need to buy a V2 metal lens ring and lens ring plate. Lens rings also work on Nodal Ninja Ultimate M1.
Make sure you always specify the correct lens type when purchasing this plastic insert. Using a wrong ring for your lens is dangerous and might damage your lens.
Contact us if you have any questions, we will be happy to help.