The function is similar to the O-ring, but for exercise and rotation, we recommend the QUAD RING. There is no twisting phenomenon during rotation and reciprocating motion, and 

It has excellent wear resistance.NBR, FKM The material is mainly used, and EPDM is sometimes used as well. The standards are AS568 and 

Used like ​. ex) AS568-221 quad ring case -> Marked as Q4221. It is often distinguished from O-ring by adding 4 in front of the size.