An anti-break lock comprising: a case having a body and a fixing hole defined through the body, two rods respectively extending from two ends of the body and two rings extending radially from the body, an axis of the rings and an axis of the rods being parallel to each other, a space defined between the two rings, the body having at least one passage which communicates with one of the rings, the ring being engaged with an engaging block, the engaging block having a recess which is located corresponding to the at least one passage and smaller than the at least one passage, a pad being engaged with the recess, the at least one passage being located at an end of the body and a resilient member and a stop pin being received in the at least one passage, the resilient member biasing the stop pin which has a first shoulder defined in a first end thereof which faces the resilient member, a second shoulder being defined in a second end of the stop pin and located corresponding to the at least one passage and the recess, a contact portion extending from the second shoulder and being located corresponding to the recess, the body having a room which communicates with the at least one passage, a resilient piece and an engaging member being received in the room, the engaging member being located corresponding to the first shoulder and biased by the resilient piece to contact the stop pin, the contact portion contacting the pad which is removed from the recess when a core is taken out, the stop pin being then pushed by the resilient member to insert the contact portion into the recess, the stop pin being then removed from the room, the engaging member being biased by the resilient piece and passing through a conjunction portion between the at least one passage and the room, the first shoulder of the stop pin being stopped by the engaging member and not being able to move to its initial position, desired lengths and numbers of the sleeves and the cores can be assembled, the two rods being connected to two sleeves of different lengths, the engaging blocks and the driving members being connected with the cores of different lengths, the sleeves having received the cores. a case having a body and a fixing hole defined through the body, two rods respectively extending from two ends of the body and two rings extending radially from the body, an axis of the rings and an axis of the rods being parallel to each other, a space defined between the two rings, the body having at least one passage which communicates with one of the rings, the ring being engaged with an engaging block, the engaging block having a recess which is located corresponding to the at least one passage and smaller than the at least one passage, a pad being engaged with the recess, the at least one passage being located at an end of the body and a resilient member and a stop pin being received in the at least one passage, the resilient member biasing the stop pin which has a first shoulder defined in a first end thereof which faces the resilient member, a second shoulder being defined in a second end of the stop pin and located corresponding to the at least one passage and the recess, a contact portion extending from the second shoulder and being located corresponding to the recess, the body having a room which communicates with the at least one passage, a resilient piece and an engaging member being received in the room, the engaging member being located corresponding to the first shoulder and biased by the resilient piece to contact the stop pin, the contact portion contacting the pad which is removed from the recess when a core is taken out, the stop pin being then pushed by the resilient member to insert the contact portion into the recess, the stop pin being then removed from the room, the engaging member being biased by the resilient piece and passing through a conjunction portion between the at least one passage and the room, the first shoulder of the stop pin being stopped by the engaging member and not being able to move to its initial position, desired lengths and numbers of the sleeves and the cores can be assembled, the two rods being connected to two sleeves of different lengths, the engaging blocks and the driving members being connected with the cores of different lengths, the sleeves having received the cores.