Help identifying insulating material

Can anyone help identify this insulating material. I always referred to it as fisch paper. I can't seem to find a source anywhere.

The needle nose are underneath to show it is slightly translucent.

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Perfectly functional but opaque fishpaper is sold at the NAPA car-parts store as "Gasket Sheet". Bring a sample so the clerk can get a fair match on the thickness. Yes, it comes from the same rolls of vulcanized fiber as fishpaper.

You may find that translucent sheet at a Starter and Alternator Repair shop. Even better, a shop that also rewinds large industrial motors.
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I bought some of that paper from AES to add a bit of security to a switch that is mounted close to a conductive surface. It is like very heavy construction paper. The curl is very persistent. If you need some I can put a piece in the mail for you.
 
DMD (dacron-mylar-dacron) is probably one of the better insulating "paper" materials around. It can take an impressive amount of electrical and physical abuse. As I've discovered at an inopportune moment, Nomex 410 is practically impossible to tear.