5/8"-11 x 13/16" x 2-1/8" Zinc Plated Steel Coarse Thread Rod Coupling Nuts

Diameter: 5/8"
Diameter 2: 13/16"
Length: 2-1/8"
Material: Steel
Finish: Zinc
Driver Type: 13/16" Wrench
Thread Size: 11 (Coarse)
Style: Hex
Type: Coupling Nut

Box of 4.

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.