Amazon.com: Genuine Unistrut P1325-EG 4 Hole 90 Degree Angle Connector Bracket for All 1-5/8" Strut Channel : Industrial & Scientific
N219EG N 219EG Superstrut 4-Hole Flat 90
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Amazon.com: 10 Pcs L Shaped 90 Degree Angle Connector Strut Channel Bracket Adjustable Corner with Slot Hole, Fit 1/2”Bolt, for All 1-5/8" Strut Channel, 4.7 mm Thickness, 2½" x 1⅝" x 1⅝",