Brand new, Bissell SpotClean Separator Stack Duck Bill Gasket, 1600034. The duck bill gasket sits on the bottom of the separator stack and float to provide a seal from the collection tank to the motor of the machine. The 3 parts act together to prevent water from entering the motor. The gasket is keyed to only work within the machine one way. If your gasket is torn or cracking it should be replaced as it could reduce suction and damage your machines motor.