An apparatus and a method for its use allow selective installation and removal of a canister such as one containing interface electronics to a mating connector on a housing, such as one containing a subsea multiphase flow meter sensor. The separately retrievable canister may contain multiphase flow meter detector electronics and is sealed, waterproof, and preferably light-weight. Installation and retrieval may be via use of an ROV and an alignment guide which acts as a guide to aid in correct positioning of the canister. The canister may be cooled by surrounding sea water and/or by insulation.