Brilliant invention for clearing clogged drains without caustic chemicals. Comes in different sizes for different drain diameters. You attach it to a hose, and say for the kitchen sink, take off the p-trap, and slide the hose down the drain pipe as far as it will go. You then turn on the hose and it builds up pressure inside the wedged bellows to the point where it releases in a burst, expanding and contracting, ka-chunk, ka-chunk . . . You can clear one obstruction and then push the hose further to get to others. It really unclogs crap. Marveloso!