An implant for the application in spinal or trauma surgery is provided that has a variable axial length, the implant including a first member and a second member guided relative to the first member to be movable relative thereto in an axial direction for adjusting an overall length of the implant; and at least one engagement member that is in a first configuration configured to engage the first member and the second member such that the first member and the second member are locked with respect to each other and in a second configuration configured to engage the first member such that the second member is movable with respect to the first member; wherein, in the second configuration, the engagement member is configured to be secured against disengagement from the first member by an abutment, and wherein the engagement member is a monolithic part.