Chesterton’s 286 Tandem Bellows Seal geometry is designed for maximum safety and reliability. The inboard seal is double balanced for high reliability in both higher and lower pressure barrier fluid environments. The outboard bellows is OD pressurized for maximum safety and pressure capability. The Chesterton 286 Dual Tandem Cartridge Bellows Seal uses a rugged proven bellows design for harsh chemical environments. It meets the most stringent requirements for sealing emissions, toxic, carcinogenic and other hazardous fluids.