Works well. Just take your time.
I used to extend wires on a Home Threater System. It is far superior to the traditional crimp butt joint. I used a heat gun toseal joint.
Cool idea. A little tricky to use but actually works very well. Slight learning curve , buts it cool.
Love these. Shrinks, seals and solders all with a heat gun and no open flame. Strip off about 3/4 of the insulation. If you dont trim enough, the shrink wrap will squeeze on the molten solder and if it has no room (removed insulation space) it can squish out.