Compression Tee Fittings are designed as an easy and economical method of connecting tubing with the assurance of a tight joint that can be rapidly connected and disconnected without leakage. By using Compression aka ball sleeve tube fittings, soldering and flaring are eliminated.compression Ball sleeve tube fitting connections are made by slipping the nut and sleeve over the tubingand inserting the tubing into the fitting. The nut is then tightened onto the fitting and the action of turning the nut compresses the inner sleeve and makes the sleeve a component part of the tubing. The angle of the compressed sleeve makes a leak proof joint between the tubing and fitting.compression fittings are sold complete with nuts and sleeves. When using plastic tube, make sure touse a plastic sleeve (delrin sleeve), inner sleeve, and tube support (aka tube insert).