Step 6 · Install Undersink Components
Move back underneath the sink. Slip the components onto the threaded bottom of the strainer body in the correct order: first the fiber or cardboard friction washer, then the rubber gasket (tapered side up towards the sink), and finally the metal locknut. Hand-tighten the locknut as much as you can. The friction washer allows the locknut to turn without twisting the rubber gasket out of place.