Brass, nickel-plated. The AG G 3/4" at the valves allows for connections of copper, precision steel, plastic pipes, and multilayer composite pipes through appropriate fittings. Additional technical specifications: Dimension: DN 15, thermostat connection size M30 x 1.5, automatic flow regulation: no, operation thermostatically with button, button color: black, suitable for single-pipe systems: yes, suitable for two-pipe systems: yes, radiator connection size: 3/4 inch (20), with curved end piece: no, with crimping set: no, with dust cap: yes, surface protection: nickel-plated, flow direction opposite: no, thermostatic preparation: yes, shortened installation length: no, pre-adjustable: yes.