I used these for my AIS installation. Raymarine includes them in some installation kits, so the guys over at The Offshore Store were able to toss a couple my way. Officially, each of these is a 3M™ Scotchlok™ IDC Butt Connector UR2.

Alls I know is they’re dang handy! As shown in the picture, they connect the tiny 24-gauge wires from my SR161 AIS receiver to the 22-gauge wires in my Raymarine NMEA cable. Don’t strip the wires…just stick them in, all the way down, and squeeze the red button closed with a plier.

The metal connector inside perforates the wire insulation to connect up to three wires. They’re gel-filled for moisture resistance, and in the picture you can see some of gel that has oozed out the unused center slot.

To finish this joint, I used a bit of surplus shrink-tube I got at the Boeing Surplus Store (is anybody else as unhappy as I am that they closed the Boeing Surplus Store?). The heat-shrink tubing doesn’t really seal anything, but it provides some mechanical reinforcement for the two cables and the 3M butt-connector.

Trust me, you do NOT want to try to strip and solder or crimp these wires in the conventional way. One false move and you’ve broken off one or two wire strands, and with wire this small, that’s about half the conductive cross-sectional area of the wire! I exaggerate, but not by much.