The Clever Coffee Dripper combines the best features of French Press and filter drip brewing, eliminating the drawbacks of each. By adding a stopper to a filter cone, the Clever Coffee Dripper combines control over steeping time with a sediment free cup. The dripper will fit on cups and thermoses with tops wider than 1.5" and less than 3.75" in diameter. Of course, if you put the dripper on a very narrow thermos you should make sure it is stable. Cleaning: Cleaning the Clever Coffee Dripper is very easy. Just dispose of the used grounds and filter and rinse. Do not allow residue to build up in the filter. Lightly scrub the cone with very hot water and a sponge or brush, taking care to clean shut off mechanism lightly from the top. If necessary, use a detergent-free cleaner designed for carafes and filter cones.