10 Pack 3/4" Compression Nut & Ferrule Combo for 3/4" OD Tube Brass Sleeve Nut3 4" Compression Nut for 3 4" Outside Diameter Tubing (10 Pack) These are 3 4" compression nuts that are designed to be used with 3 4" outside diameter tube and a 3 4" compression fitting. This nut is made out of solid brass and comes with the ferrule sleeve. The sleeve comes pre pressed into the nut so you won't have to deal with any misalignment issues when installing your new tubing. This fitting is also sometimes referred to as a captive sleeve