The clamping bores of GN 167 wide base plate connector clamps are not machined and specially designed for construction tubings GN 990 or DIN 2391, DIN 2395 and DIN 2462 respectively.
The square versions are also suitable for profile systems.
The standard clamping screws are socket cap screws DIN 912. They can be replaced by clamping kits GN 911 (article code see table of dimensions).