A clamping collar including: a belt comprising a strip and two free ends, each of said the ends being curved back to form a loop and each loop being defined by an outer belt portion and by an underlying inner belt portion; and a tightening system suitable for bringing the loops closer together and for tightening the belt; and in which each of ends of the belt is curved back towards the inside of the collar, the inner belt portion being extended beyond the loop, under the strip, and the outer belt portion presenting a tightening wall with which the tightening system, comes into engagement.