Key switch must be hardwired to garage door opener.   Find suitable location and drill 7/8″ diameter hole to a depth of at least 2 5/8.   Drill 1/4″ diameter hole, as required, to accommodate lead-in wire.   Opener is activated by inserting key and turning.   Key is spring-loaded to return to center of position for key removal.   Contacts are completely isolated from key and cylinder assembly.