Closure arrangement, in particular for use in the closing of open ended cylinders. An end cap (20) or plug (50) is used to close the end of a cylinder (10), the cap (20) or plug (50) being locked in place by a flexible locking member (32) inserted into a circumferential cavity (30) between the end cap (20) or plug (50) and the cylinder (10) via a passage (40) interconnecting the groove (12, 22) and the exterior of the arrangement.
