Providing the power beneath the screw-down case back is Seiko Calibre 6R15, an automatic movement that oscillates at 21,600 vibrations per hour and offers a healthy power reserve of 50 hours. It’s a reliable movement found in a number of other Seiko dive watches as well as some of the brand’s Presage models and is known for its precision. It’s not a hi-beat movement like the SLA025, of course, but it fits well with the superb quality/price ratio that this watch offers.