1. Slide the fittings onto the trap arm in this order: slip nut (threads first), another slip nut (threads last), and a slip washer (beveled side last). Push the trap arm about 1 1/2" into the drain pipe.

2. Slide the slip nut onto the sink tailpiece (threads down), then a washer (beveled-side down). Push the long end of the trap bend onto the tailpiece and slide it up until the short end meets the trap arm. Slide the washer and nut down the tailpiece and tighten the nut onto the bend by hand.

3. Move the position of the trap arm to align it with the short end of the trap bend, then tighten all of the nuts with channel-type pliers or a pipe wrench, but do not overtighten. Test the drain by running water. If it leaks, tighten the slip nuts another 1/4 turn.