BSP 1/4" Hexagon Lock Nut / Back Nut T316 (A4) Marine Grade Stainless Steel Approximate Dimensions Across Flats: 23 mm Thickness: 8 mm Thread: according to EN 10226-1 (EX ISO 7-1) (conical male thread, cylindric female thread) Taper 1:16 on diameter Angle of threads 55° Maximum operating pressure 150 lbs = 10,34 Bar PN 10