Materials: The shell is made of high quality nylon. It keeps open flame and is electrically insulating. The conductive piece is copper, which has perfect electrical conductivity. Quick Installation: Simply insert insulated cables and push closed, skid by special contacts which is unnecessary stripping. Makes tapping into an existing wire a quick and easy job, no special tools needed. Wide Application: Quick splice T-tap connectors are widely used in the wire connection of home ,car and medical industry wire connecting use. Wire Range: 0.5-1.0 mm/22-16 A.W.G(Red); 0.75-2.5 mm/ 18-14 A.W.G(Blue); 4.0 mm / 12-10 A.W.G(Yellow). Package includes: 60 T-branch connectors and 60 flat plugs included. Comes in blue, red, yellow three different colors, easy to identify and classify.