Its my first time to come accross this Octa model so I thought of posting it here (sorry if this is already old news). The material is taken from the magazine CHRONOS Japanese Edition (please delete post if inappropriate)
Octa Automatic Reserve (direct translation) in pt. Diameter is 40mm
Cal. 1300-3 Bi-directional winding automatic movement with about 5-day power reserve.
Best Regards,
Kazumi