Heat Shrink Tubing

Gardner Bender black heat shrink tubing from 3/32 to 3/4 in. diameter, in multi-packs. Size it by the largest thing the tube has to slide over before it shrinks, then check that the shrunk diameter is small enough to grip the thinnest part of the joint. It goes on the wire before the connection is made, not after — a mistake everybody makes exactly once. Heat it with a heat gun rather than a flame, since a torch scorches the tubing and can leave a pinhole in the insulation.