The records were played on turntables, but since the timing – the clock synchronization – between the two SIGSALY terminals had to be precise, the turntables were by no means just ordinary record-players. The rotation rate of the turntables was carefully controlled, and the records were started at highly specific times, based on precision time-of-day clock standards. Since each record only provided 12 minutes of key, each SIGSALY had two turntables, with a second record "queued up" while the first was "playing".