The surface is plated with chromium plating, making it wear-resistant and durable. The Kaiser Thread Adapter isa1/4 to 3/8 inches convert screw adapter for cameras, tripods, ball heads, light stands, flash brackets and monopods, etc. This is aspecially designed tripod convert screw adapter.Key features:Inside diameter: 1/4 inch(British system)Outside diameter: 3/8 inch(British system)Material: Copper