Center Hole Stainless Steel Ball Outer Dia 3mm-60mm Smooth Small Balls for DIY. Ball Diameter : 3mm to 60mm. Bore Diameter : 1.1mm – 5mm. Steel ball standard: GB. This drill ball is a hole drilled on a solid steel ball, made of stainless steel. And the inner hole diameter will have an error of plus or minus 0.1mm. Corrosion resistance, high hardness, no rust. Solid stainless steel through-hole ball, no thread, non-magnetic or weakly magnetic. Can be used for decorations, teaching experiments, mechanical parts, hardware accessories, DIY bead bracelets, etc. (Except some countries and APO/FPO). Service transit time is provided by the carrier and excludes weekends and holidays. Transit times may vary, particularly during the holiday. We care about our valued buyers, if you have any questions, our customer service staffs will be very glad to help you. We try our best to reply to your emails as soon as possible, however, due to high volume of daily incoming emails. And time zone difference, we may not be able to reply your emails immediately. Feedback is very important to us.