RinbowImaging 37mm Metal Screw-in Lens Cap / 37MM Stack Cap Protect store Filter case This item can work as a 37mm Metal Screw-in Lens Cap, and it can also work as a 37mm Filter Stack Case. Filter case protect filters from dust and scratches while they are not being used Simply screw the filters together, then screw these stack caps on the top and bottom. Compatible to lens with 37mm thread size, and 37mm Filters