The Fantasea G7X and G7X Mark II includes both a black and a white o-ring on the housing. Prior to each dive both o-rings should be visually inspected for damage, debris, hair, etc. Do not remove the white o-ring from the housing unless you see damage to the o-ring. The black o-ring should be carefully removed, cleaned and lubricated prior to your dives to ensure a good seal.
We recommend replacing the black o-ring every 200-300 dives or every 1-2 years depending on wear. The white o-ring will only ever need to be replaced if it shows visible signs of damage.
