BOV diluent hose adapter for Divesoft BOV with integrated ADV, which allows for a single hose to be used. In case your BOV is equipped with Single Hose Adapter, DO NOT use wrench to tighten it. Finger tight is enough in this case. SHA does not screw all the way in on the lower (2nd stage) thread, few screw threads will be always visible. Overtightening will cause the BOV and MAV to warp which leads to water/gas leaks and damage to the unit itself.