Abstract: A combination lock having a box inside which is located a sliding latch having a ratchet operated by a pinion operated from outside. The pinion being slidable to enter a round hole in a plurality of rotating members operating as a coding device, the pinion being adapted to rotate only when it is in said round holes. The combination members have the remaining holes of a section that blocks the pinion rotation so that only when all the combination members offer their circular holes is possible to rotate the pinion and so operate the latch.