Genuine Unistrut P2458-18 GR 2-Hole Tubular Knee Brace Perma-Green III- Green Powder Coated Finish for All 1-5/8" Strut Channel Genuine UNISTRUT Brand 18 Inch 2 Hole Steel Tubular Knee Brace For Use With 1/2" bolt in ALL 1-5/8" Series Strut Channels 17/32" Diameter Hole; 1" Diameter Tube Finish: Perma-Green III- Green Powder Coated Finish