Bullet connectors are small bullet-shaped metal pieces that can be crimped onto the ends of wires. They come in both female and male versions, so when two wires are outfitted with the opposing versions, you can connect the wires together by snapping the bullet connectors together. Bullet connectors are typically used in car audio applications, but they're suitable for many different types of electrical and electronic connections. Crimping bullet connectors onto wires is a fairly simple process.
Remove about 1/4 inch of the insulation from the end of your wire with a set of wire strippers. Twist the strands of bare wire between your fingers to create a tight bundle of wires.
Slide the open end of the bullet connector over the bare end of the wire. Bullet connectors are built for different gauges—thickness—of wires. Be sure that the connectors you use are the right size for your wire.
Place the jaws of your crimp tool over the end of the bullet connector where the wire was inserted. Close the handle of the crimp tool firmly to crimp the metal of the connector firmly onto the wire.