The collar is made from a metal strip formed into a loop, and has a fastening stud and an ear that project radially. The ear is provided with an aperture into which a free end portion of the stud can be inserted for the purposes of fastening and of tightening the collar. The collar further has engagement surfaces for engaging with a tightening tool, which surfaces project radially and are situated respectively behind the ear and behind the stud. The stud and the engagement surface that is situated behind the stud are formed in a common projection and have side cheeks that are raised relative to the plane of the strip, and that are common to them. The ear is also formed by a projection.