soldercon red 50-pack

The best waterproof low-voltage wire connector on the market!
 
The "red" is the most common size, good for AWG 22-18.
 
Great for making a smooth in-line permanent wire connection without marrets or other bulky connectors.
 
All you need is a lighter or a heat-gun with a narrow nozzle.
Strip ech wire about 1/4"
Insert wires on each side of the connector, overlapping the stripped sections inside the metal tube.
Use a standard lighter or heat-gun to heat up the tube, in a back and forth motion for even heat.
The plastic tube will  shrink. When the metal tuble melts, stop applying heat and hold in place until everything cools.

NOTE: the connector will be waterproof if there is ONLY ONE wire per side. Multiple wires per side can be used for indoor applications.