When a manufacturer says Beam Clamp, they mean the family of clamps that attach members to a steel support beam. While there are many different kinds of beam clamps, the Window Clamp is the beam clamp with U-bolts. Whether you use Kindorf, PowerStrut, B-Line or some other strut manufacturer, they all offer Window Clamps of similar construction because there is generally only one way to mechanically make these things happen. As an aside, when a distributor or electrician refers to a Beam Clamp, they typically mean the "C" style clamp that screws tight to the flange of a beam and has a threaded hole to accept threaded rod. The Window Clamp, however, is the style that U-bolts the strut to the support beam.