9423M8 vault type door closing mechanisms for single or multi door enclosure with openings from 61 to 90 inches. This M1 mechanical interlock kit is designed to interlock a Class 9422 handle mechanism with the Type M8 door closing mechanism. This kit prevents opening the master door (or single door) with the disconnect handle in the ON position. The kit makes it mandatory to use a screwdriver to gain entry to the enclosure, regardless of the disconnect handle position.