Aqua Signal Heavy Duty Round Base for Plug-In Pole Lights Universal style base for plug-in pole navigation lights 2 or 3 pin Aluminum socket provides strength and durability compared to plastic bases Rubber snap on cover protects socket when not in use For most locking collar style plug-in pole lights including Aqua Signal series 22 All-Round and BiColor Pole Lights 2 1/4" O.D.