Utilize Discount Strut Accessories 3/8" x 7/16" Electro-Galvanized Steel Square Strut Washers to connect threaded rods & other strut fittings to channels. The 304 stainless steel material is ideal for outdoor use, highly resistant to corrosion, & great for chemical or saltwater applications. Finish: ST304 Size: Bolt = 3/8"; Hole = 7/16"