I got something like this once. Didn't do a thing unless you hit it with a MASSIVE magnetic field. I currently use an MV-95 viewer from Sigma Hi-Chemical Inc. Japan.
From: Association for Recorded Sound Discussion List [mailto:[log in to unmask]] On Behalf Of Jeff Willens
Sent: Friday, February 17, 2017 4:10 PM
To: [log in to unmask]
Subject: [ARSCLIST] Magnetic Green Film
So I've been seeing this thing on Ebay, and I'm wondering if it might be a good substitute for the Arnold magnetic viewers we currently use to view tape tracks.
It's a magnetic viewing card made of green film.