Remove the knockout plug with a hammer and screwdriver.
Connect the end of the drain hose a to the air gap b with the hose clamp provided. Move the clamp into position and tighten it with a flat-blade screwdriver.
This avoids water being siphoned from the tub.

If it is not connected, attach the rubber hose connector to the disposal or waste tee with a hose clamp (not provided).