Sea & Sea SX extention ring

Can anyone tell me how long the Sea & Sea SX extention ring is?

Sea & Sea have a 40 mm and a 22 mm but I wonder why this one is not listed in mm?

Thanks

Can anyone tell me how long the Sea & Sea SX extention ring is?

 

Sea & Sea have a 40 mm and a 22 mm but I wonder why this one is not listed in mm?

 

Thanks

Just measured mine, and it looks like you get 19 to 20mm of extention with it, so fractionally narrower than the 22mm

Just measured mine, and it looks like you get 19 to 20mm of extention with it, so fractionally narrower than the 22mm

The Sea & Sea website lists it at 35.5mm of which approximately 16mm goes into the housing so 19mm - 20mm should be a safe number.