Abstract: A lock comprising a housing having an indoor side and an outdoor side; an axis passing through the housing from the indoor side to the outdoor side. A main bolt having a bolt portion and a latch portion, the main bolt being displaceable into and out of the housing. A double acting actuating mechanism coupled to the main bolt by the axis, the axis having a first pin to actuate the actuating mechanism and a second pin to actuate the actuating mechanism, the first pin and the second pin displacing the main bolt into and out of the housing. Locking means for preventing displacement of the main bolt. A combination hub being disposed in the housing, the combination hub releasing the locking means when a combination key is introduced into the combination hub. Means for limiting the displacement of the main bolt upon movement out of the housing such that only the latch portion is exposed out of the housing.