link 42 can extend practically from wall to wall on the other hand the placement of the two clamping jaws 6 in hollow profile bar 10 of fig1 reveals owing to the curvature of the circularly cylindrical hollow profile bar 10 the clamping jaws 6 are unable to grip shorter clamping strips securely enough and thus appear to be unstable due to their distance from inner wall 26 so that the broad base is appropriate the distribution of the inner webs 27 about the circumference depends on the technical object to be achieved in the arrangements of fig1 and 2 the inner webs 27 are realized as comparatively long and are therefore merely disposed at a pitch of 45 angular degrees thus comparatively massive and tall links 42 can still be mounted without colliding with the inner webs the arrangement of the inner webs is such that they are aligned with the casing grooves 14 they therefore stiffen the tubular wall 11 midway between two outer webs 12 this is important when the link 42 laps two inner webs 12 with its tong legs 34 in this case a tubular wall 11 that was implemented as thin might collapse inward the broad base 29 reliably prevents this the pitch 28 of the inner webs 27 in this case is twice that of the outer.