One end has a 12.7mm (1/2") diameter stainless steel pin for attachment to a clamp or base. Attach electrode holder to other end. Molded of chemical and corrosion resistant acetal copolymer links with ball-and-socket joints. Base and electrode holder sold separately. The arm is 46cm (18") x 25mm (1") in diameter. Arm can hold and position a pH meter or similar tools Chemical resistant $98.55 Each