The Pi20 series is a one-piece stainless steel ring grating with 20 µm pitch incremental graduations engraved on the cylinder and an optical reference mark. It is available in three sizes, 75mm, 100mm and 300mm in diameter. The rotary encoders have excellent mounting accuracy and feature a tapered mounting system that reduces the need for high-tolerance machined parts and eliminates center misalignment. It has the characteristics of large inner diameter and flexible installation. It uses a non-contact form of reading, eliminating backlash, torsional errors and other mechanical hysteresis errors inherent in traditional enclosed gratings. It fits the RX2 readhead.