Stainless steel with the hole for the sheet suitable for use with sheet hook. The hole for the sheet is mechanically de-burred to ensure the sheet does not abrade or chafe. The item is then tumbled in abrasive to remove all external sharp edges. If it is too slack on boom use pliers to gently squash the hole to an elliptical shape until the grip is good. When you are sure the part is properly positioned on the rig and aligned symmetrically use a spot of cyanoacrylate glue to lock in place.