The Conn-Selmer 8” bell cover with MERV-13 filter is built to filter air particulates coming from the instrument. Designed to fit most models of tenor trombone, tenor saxophone and baritone saxophone, the 8” bell cover doesn’t alter the pitch or affect the quality of sound from the instrument. Made from a double-layered stretch nylon with an elastic band, the 8” cover is easy to install or remove from the bell of the instrument and features a removable, hand-washable MERV-13 filter.