Abstract: A security lock for a computer having a wall (42) with a rectangular or circular hole (43; 44) therethrough comprises a body (11) to which a security cable (16) is secured, the body having a push button lock (18) therein, activation of the lock causing a pair of retention arms (24) to move linearly apart against spring means (35; 50). The arms have hook-like terminal portions (33) at the exterior of the body (11) and activation of the lock after the portions (33) have been passed through the hole (43; 44) causes the arms to move apart so that the portions (33) locate “behind” the hole, thereby securing the security lock to the computer. The security lock has is body (11) secured against rotation relative to the lock (18), with the body and lock being freely rotatable relative to the retention arms.