After the classic 6E5 (the one that actually looks like an eye) this is the most common type of magic eye tube. A similar Chinese NOS 6E2 can be had for $10. It's junk but none of them last forever.
If you're interested, here's a fantastic web site with tons of info and animations of the patterns:
Yeah, I shared that link before but it may be of interest to someone who didn't see it.
I don't mean to criticize a seller whose first language isn't English but the price is a tad high. o_O
Terry Bowman, KA4HJH
"The Mac Doctor"
"If only you could see what I've seen with your eyes."—Roy Batty, Blade Runner