Test Balls, chrome alloy steel, made from AISI standard steel No. E-52100, with diameter of 12.7 mm (0.5 in.) Grade 25 EP (Extra Polish). Such balls are described in ANSI B3.12. The extra-polish finish is not described in that specification. The Rockwell C hardness shall be 64 to 66, a closer limit than is found in the ANSI requirement.

Pack of 500 test balls for use with Seta-Shell 4-Ball Lubricant Testers. For performing tests specified in ASTM D2266, ASTM D2596, ASTM D2783, ASTM D4172.