A needle device (10, 300) comprising: a needle hub with a needle with a needle tip extending in a distal direction; a catheter hub (18, 302) distal of the needle hub and comprising an interior cavity (142, 334) and a catheter tube (16, 304) extending distally of a distal end of the catheter hub (18, 302); wherein the needle comprises a change in profile, a guard housing located at least in part between the catheter hub (18, 302) and the needle hub and having a movable arm; a needle guard comprising a proximal wall having a perimeter defining a proximal opening located in the guard housing; a release element located at least partially inside the guard housing and in mechanical communication with the movable arm, wherein the release element comprises at least one lifter; wherein the needle projects through the guard housing, the catheter hub (18, 302), and the catheter tube (16, 304) and out a distal end of the catheter tube (16, 304) in a ready to use position; and wherein part of the arm on the guard housing engages an exterior of the catheter hub (18, 302) and the arm is deflectable by action of the release element, which is movable by action of the needle to release the engagement between the part of the arm and the exterior of the catheter hub (18, 302); and wherein the change of profile engages the perimeter defining the opening on the needle guard when the needle moves in a proximal direction; characterized in that the needle guard pushes on the release element, which causes the at least one lifter to move the arm to separate from the catheter hub (18, 302), upon retraction of the needle guard by the needle. a needle hub with a needle with a needle tip extending in a distal direction; a catheter hub (18, 302) distal of the needle hub and comprising an interior cavity (142, 334) and a catheter tube (16, 304) extending distally of a distal end of the catheter hub (18, 302); wherein the needle comprises a change in profile, a guard housing located at least in part between the catheter hub (18, 302) and the needle hub and having a movable arm; a needle guard comprising a proximal wall having a perimeter defining a proximal opening located in the guard housing; a release element located at least partially inside the guard housing and in mechanical communication with the movable arm, wherein the release element comprises at least one lifter; wherein the needle projects through the guard housing, the catheter hub (18, 302), and the catheter tube (16, 304) and out a distal end of the catheter tube (16, 304) in a ready to use position; and wherein part of the arm on the guard housing engages an exterior of the catheter hub (18, 302) and the arm is deflectable by action of the release element, which is movable by action of the needle to release the engagement between the part of the arm and the exterior of the catheter hub (18, 302); and wherein the change of profile engages the perimeter defining the opening on the needle guard when the needle moves in a proximal direction; characterized in that the needle guard pushes on the release element, which causes the at least one lifter to move the arm to separate from the catheter hub (18, 302), upon retraction of the needle guard by the needle.