A closure is shown and described, preferably for an orthosis, which has a belt assembly, having a first closure part (1) and a second closure part (21), which can be releasably connected to one another, wherein the first and the second closure parts (1, 21) have connecting means for belts of the belt assembly, wherein the first closure part (1) has a pin (3), wherein the second closure part (21) has a connection end (23) and a coupling end (25), and between the connection end (23) and the coupling end (25) a guide track (37) extending in a closure plane is provided, which extends from an entrance opening (41) to a guide track end (43), wherein the pin (3) has a first section (7) and a second section (9), wherein the dimensions of the first section (7) perpendicular to the direction of extension of the pin (3) correspond to the dimensions of the guide track (37) in the closure plane at the guide track end (43), and wherein the dimensions of the second section (9) perpendicular to the direction of extension of the pin (3) are greater than the dimensions of the guide track (37) at the guide track end (43), so that the second section (9) restricts a movement of the pin (3) relative to the second closure part (21) perpendicular to the closure plane.