I've been using it for years - simple, functional.It's safe and easy to do. If you don't have a heat gun, use a hair dryer on low power to shrink the new wrap in place having removed the torn one.
The tricky bit for me is holding the insulator ring in place. It can easily blow off and you really need to make sure it's included in the re-wrap. I use a pair of ceramic tweezers to keep it steady until the wrap has curled around it, holding it from escaping. Then just keep heating it until the wrap shrinks tightly around the whole battery.
$2.08 18650 Battery Insulators Adhesive Paper Cardboard (100-Pack) 100-pack - water resistant / wear resistant / easy peel & stick at FastTech - Free Shipping

