Single seal/Unbalanced/Dependent on direction of rota- tion/To EN12756(DIN24960). 120 series is derived from JF-M3N series.It is driven by hook nail on the end of the spring.It has a simple structure and is easy to install. Proper attention shall be paid on the direction of rotation while using. It is often used in chemical pumps, sewage pumps and submerged pumps.