1/4"-20 x 7/8" Zinc Plated Steel Coarse Thread Rod Coupling Nuts

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.