I have a precursor of this. It is black and a rubber based compound. It was called self amalgamating tape or self vulcanising tape. Still available at Bunnings and Masters.
It is great for a waterproof seal and a little goes a long way as it is best applied whilst stretched.
However, it should be noted that once it has been on for a 10 minutes or more it has to be cut off.
Good insulating properties, good under the bonnet of a car or anywhere else there are highish temperatures. Won't start coming undone like normal insulation tape does when heated.
Been using it since the late 80's to early 90's.
Always keep some handy.
