CNC precision machined. Protective coated for corrosion resistance (Bright Zinc Plated). Specification: ID X OD X THICKNESS. M5 X 18 X 2.8, M6 X 19 X 3.15, M8 X 20.5 X 3.15, M10 X 24 X 4.8, M12 X 28.5 X 5.7, M16 X 36.7 X 7.1, 1/4" ( 6.4) X 17.3 X 3.6, 5/16" (7.94) X 20.5 X 4.26, 7/16" (11.11) X 28.4 X 5.6, 1/2" (12.7) X 30 X 5.8.
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