The types BA and BB are commonly used in pairs to clamp two steel sections together. The type BA has a recessed top to grip the head of a grade 8.8 setscrew or bolt. This allows a nut and washer to be tightened down on to the flat top of the BB using one tool only.
Both clamps are available with three tail lengths, 1, 2 or 3 (dim E). This should be as near to the thickness of steel it is clamping on or slightly less if an exact match is not possible. Packing pieces BF1, BG1 and BH1 can be used in combination with the tail length to achieve a match to the steel flange. BA and BB types are suitable for parallel flanges and flanges up to 8 degrees taper. They can also be used on their own if one piece of the steelwork has been pre-drilled.