This is the Steeldive SD1964 which is a homage to the Sea-Dweller which was developed in late 1967 to counteract the problems caused by decompression when Helium atoms inside a pressure chamber can work their way inside a watch. During decompression, the pressure inside the chamber can decrease more rapidly than the pressure inside the watch case. This can, in some cases, cause the watch crystal to pop off. The helium-release valve allows helium to escape from the case during decompression preventing damage to the watch.Although resembling the Submariner, it is a bigger watch and has more presence on the wrist.
 
The Specs - 
Sapphire Crystal Glass
NH35 Automatic Movement
120 Click Rotational Ceramic Bezel
1000m Water Resistance
Helium Escape Valve
Screwdown Crown
Screwback Case
316L Stainless Steel Case
Stainless Steel Strap fitted with extra Branded Rubber Strap
Hacking Movement
C3 Luminova on the face
Lug Width - 22mm
Case Diameter - 45.4mm
Lug to Lug - 54.85mm
Case Thickness - 17.1mm
Weight - 180g
Hard Presentation Box and warranty card
 
We supply an extra rubber strap with fitting tool and pins so you can change the look of the watch.