A turnstile is a kind of gate that allows one person to pass at a time. Most
turnstiles are at waist height, but there also exist full-height turnstiles to prevent
people from jumping over. Such turnstiles operate in a manner similar to
revolving doors, but look more like a set of spikes emanating from a central
pole. By what name, bringing to mind a similar-looking medieval device, are
full-height turnstiles also known?


HINT:A famous BAND shares its name with them.