If you own a Seiko Turtle or PADI Turtle (SRP773, SRP775, SRP777, SRP779, SRP787, SRPA21, SRPC44, SRPC49), this is the caseback gasket you need. This same gasket also fits the vintage 6309 Turtle and the legendary 6105 Captain Willard — three generations of iconic Seiko divers, one gasket design that spans decades. The caseback gasket sits in the groove between the caseback and the case body, creating a watertight seal that protects the movement from moisture and dust. Over time, rubber gaskets age, dry out, and lose their elasticity — when that happens, your watch loses its water resistance and the movement is at risk. Replacing the gasket restores the seal and brings your diver back to proper working condition.
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