The Tuna
link comes packing a brilliant L-shaped rubber gasket that keeps helium out. The in-house 8L35 movement is made by Grand Seiko in its legendary SII facility in Morioka.
link The 26-jewel, 50-hour power reserve, 28,800 bpm 8L35 is essentially an un-bedazzled 9S55. Remember, it's
link a monocoque case with no display, so you'll never see the movement anyhow.