Abstract: A cylindrical lock comprising an U-shaped shackle, a cylindrical housing containing a hollow tube consisting of two elongate semi-round plates and a lock member, two legs of the shackle having a cone-shaped end and two inclined slots to pushingly insert in two holes in the hollow tube to engage stopping edges of the two notches of the elongate plates through opposite movement of the two elongate plates for locking and the stopping edges of the two notches disengaging from the slots of the shackle by movement of the two elongate plates moved by the lock member rotated by a key.