A hose clamp for limited diameters, in the form of an open band ring having overlapping band ends, is manufactured from the band material of an insert as is used in conventional hose clamps for bridging an ear gap, such insert being typically made of steel according to DIN 1.4310 having a thickness of 0.3 mm. An opening is provided near one band end and a hook for engaging the opening is provided near the other band end. For closing this hose clamp, a gripper-type tool is used, the two jaws of which, in the closed condition, constitute an essentially uninterrupted inner surface having a diameter corresponding to the outer diameter of the closed hose clamp.