The clamps are built with Stainless Steel 6-32NC Socket Head Cap Screws (SHCS) requiring 7/64 tool.
The BR-332-SJC-7.0 is designed for Code 332 rail that has a flange width from 6.5mm-7.5mm. That includes most of the 332 rail on the market.
This is a Brass clamp.
Price shown is per each clamp.