Baritone Sax

The baritone saxophone or "bari sax" (commonly abbreviated bs or bars to distinguish it from the less frequently used bass saxophone) is one of the largest members of the saxophone family, only being smaller than the bass, contrabass and subcontrabass saxophones. It weighs approximately 75 pounds. It is the lowest-pitched saxophone in common use, and uses a mouthpiece, reed, and ligature that are larger than the tenor, alto and soprano saxophones, the other commonly found members of the family. The baritone saxophone is commonly used in classical music (such as concert bands, chamber music and solo repertoire), military bands, marching bands and jazz (such as big bands, jazz combos, etc.).

Note: this information was paraphrased from Wikipedia.