Best Padlock, Brass Body, 3/8" Shackle Diameter, 4" Shackle Clearance. 6/7 - Pin SCIP Prep, Less Core. Non-Key Retaining 41B SERIES Specifications Case– Machined from solid extruded brass. Standard finish is 626 satin chromium plated. Width– 1 15/16" Length– 2 1/16" Thickness– 7/8" Shackle– The shackle locks at both heel and toe. The length of shackle opening is measured from top of case to inside of shackle when padlock is locked. Material– Bronze or stainless steel. Diameter– 3/8" Width of opening– 7/8" ASTM F883– Meets Grade 3 with stainless steel shackle, grade 4 with XSPL shackle. ASTM F883– Meets Grade 6 for option E. (Corrosion resistance. ASTM F883– Meets Grade 6 for shackle cutting force with XSPL shackle option.