If you're looking for a low-profile mounting base for a Multi-Reticle Finderscope, this is it. This will mount to a Stellarvue CNC clamshell ring (not hinged rings), any flat or curved surface. It mounts with two #10 screws. Comes with two 10-32 socket head cap screws for mounting to the Stellarvue CNC clamshell. Note: This is for the multi-reticle finders it does not fit Stellarvue F1001 Red Dot Finders.