Tuba

The tuba (bass) is the lowest-pitched musical instrument in the brass family. Tubas are most commonly found in B♭ ( but do get made in various other pitches F, E♭, C,). The tuba is generally constructed of brass, which is either unfinished,  lacquered or  with gold, nickel or silver. Unfinished brass will tarnish eventually and must be periodically polished to maintain its appearance.