Clamp ring comprising a metal band (1) which is wound round upon itself. One of its ends is hook-shaped (2) while its other end has a projecting lug (3) for the hooking over of the free edge (4) of the hook. The lug (3) has a boss (6) on its face (5) where the free edge (4) of the hook rests after being hooked over, which boss is preferably positioned more or less in the middle of the width of the lug, while the free edge (4) of the hook has a notch (4a) of a complementary shape to the boss of the lug. …<IMAGE>…
