Square Bolt (C Bolt) M6 x 18 mm Thread, 51 x 43 mm Internal Dimensions - T316 (A4) Stainless Steel Complete with 1 full nut and 1 half nut on each leg Ideal for fastening two off 2525 RHS (Rectangular hollow Section) in landscape orientation, but of course will have many uses Please refer to diagram for details (all measurements in mm): RHS : 2525 A = 6 mm B = 51 mm C = 43 mm D = 18 mm Centers = 57 mm Our manufacturing tolerances are + / - 1 mm) We use roll threading so the diameter of the bar is usually less than the thread size. Please ask if unsure