The Aqualung i450T computer has a user serviceable battery but the manual states the rear cover seal/o-ring must be replaced. The manual does NOT reference the part number. I contacted Aqualung and found the seal is only available as part of a battery kit. Screws, silicon paste and a battery (CR2450). The kit number is #NS911149 and is only available through the Aqualung dealer network in the US.