The collar comprises a metal belt (10) having a projecting lug (18) in the vicinity of a first end (10A), and a hook (14) in the vicinity of a second end (10B), which hook has a front wall (15) designed to be retained against a rear wall (19) of the lug (18) while the hook (14) is hooked onto the lug (18) in order to maintain the collar in the tightened state. Seen from above, the rear wall (19) of the lug (18) has a V-shape having its tip (19A) pointing (S) away from the hook (14), and the front wall (15) of the hook (14) has hooking sides (15B) that are inclined relative to the transverse direction of the belt to match the inclination of the branches (19B) of the V-shape.