DESCRIZIONE
An adjustable circumference seal includes an envelope having an outer layer and an inner layer, with the inner layer defining a sealing surface. A circumferential closure is provided for constricting the inner layer of the envelope and thereby adjusting a circumference of the inner layer of the envelope. The closure includes a band having a first end and a second end, with a first cord guide at the first end and a second cord guide at the second end. A cord is threaded from the outer layer through a cord channel in the envelope, through the first cord guide of the band, through the second cord guide of the band and back through the cord channel. By pulling the cord, the circumference of the inner layer of the envelope is reduced until the sealing surface is brought into a sealing engagement. A cord lock for maintains the cord in a selected position.