I'd really encourage you to tear one apart and see what you think. I got about 30 four feet long a couple years ago. The "tar" was brittle and easily beat off the copper windings. I forget how much copper I wound up with from the as I got other ballasts and aluminum cases at the same time but it was a nice check. I did like zito said. Lined up a bunch of the and opened the cases with the grinder. Then peeled them open like they were on a hinge. Then there was two chunks of connected copper that just lifted out.