Dual, stationary spring, pusher seal in modular cartridge design, with parts interchangeable with other ISC versions. The seals are arranged in tandem configuration, but are double balanced to allow both pressurized and unpressurized operation. Unique high efficiency standard pumping feature allows cooler seal operation for increased reliability. Available in a wide range of materials. Suitable for most common ANSI standard bore, ANSI enlarged bore and DIN standard chemical pumps.