You would want a HRL 5 A 33.7 PP UNC. The first 3 letters tell you the clamp series. the number 5 indicates the family size of the clamp. The A tells you the arrangement. In this case a top plate, clamp pair, weld plate, and bolts. The 33.7 is the metric equivalent of a bore to hole 1” pipe, all of the bore measurements are in mm in our model codes. The PP is the clamp pair material Polypropylene, and the UNC stands for standard threads. You can also find all this information in our online catalog.