Made from plastic but very sturdy, comes with all the fittings. An excellent price/performance hop unit. Arm pin is metal and rotary wheel has the right amount of tension.
I recommend using a tiny amount of silicon grease on the wheel where it meets the oring.
Unlike many cheaper hop chambers on the market which use a molded nub on the arm, the ZCI version uses the concave style design, good for Omega nubs etc.