Abstract: A cylinder lock comprises two barrels in axial alignment on either side of a web. Each barrel is formed as two opposed elements disposed in either side of a longitudinal plane in which the keyhole is formed by confronting surfaces of the opposed elements. The web is engageable with internal end parts of the barrel elements and each barrel comprises tumblers received in the barrel and operable by a key inserted in the keyhole. A one-piece lock block has a central recess through which the web passes and two rectangular parts on either side of the recess each having a narrow top surface contiguous with one of the barrels. Pins are received in bores in the lock block and the pins are spring-biased to lock the barrels when the key is absent. Two housing members each engage over one of the rectangular parts and the corresponding barrel to maintain the barrels in contact with these parts.