B+ motorhomes

There is such a heat shrink wrap. I don't know about smaller sizes, but when I worked as an industrial electrician we would sometimes have to splice cables that were connected at both ends hundreds of feet away. The shrink wrap wrapped around the splice like a slit plastic tube with two turned back edges, and had a metal "zipper" that slipped over the edges and held both sides together as heat was applied with heat guns to shrink the product onto the wires beneath.

Likely the company, RayChem makes smaller sizes for smaller cables.