Diameter: 1/4" Length: 7/8" Material: Steel Finish: Zinc Driver Type: 3/8" Wrench Thread Size: 20 (Coarse) Style: Hex Type: Coupling Nut Side A: 3/8" Side B: 7/8" Box of 20. A coupling nut is a long nut tapped from each side to meet in the middle, rather than all the way through in the same direction, used to connect two threaded rods end to end.
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