The recorder is a family of woodwind musical instruments of the group known as fipple flutes or internal duct flutes—whistle-like instruments that include the tin whistle. The recorder is end-blown, and the mouth of the instrument is constricted by a wooden plug, known as a block or fipple. It is distinguished from other members of the family by having holes for seven fingers (the lower one or two often doubled to facilitate the production of semitones) and one for the thumb of the uppermost hand. The bore of the recorder can be tapered slightly, being widest at the mouthpiece end and narrowest towards the foot on Baroque recorders. Renaissance-era instruments also taper, but generally have more nearly cylindrical bores. Recorders can be made out of wood, plastic, or ivory.