A transitional mounting adaptor to connect a pool main drain to a pool main drain cover with or without water in the pool. The adaptor consists of a trim ring with four cardinal point screw slots (NSEW) molded to a perpendicular mounting ring with three equally spaced, threaded pointed thumb screws, passing perpendicularly thru the mounting ring, via a series of threaded mounting holes, creating three pressure points which secures the adaptor to the main drain pot. The cardinal point screw slots in any position will receive coarse thread main drain screws used for mounting a main drain cover onto the trim ring. Further, the edge of the trim ring is bull-nosed. The cardinal point screw slots of the trim ring can also be used to mechanically fasten the adaptor to a main drain pot. The adaptor allows water to pass thru the trim ring, thru the mounting ring, and continue thru the main drain, as with the normal functioning of pool water flow.