The first pic is the type we used to see at our barbershop. So it's almoat 50+ years old, and it still competes - maybe better - with the modern world. Top-notch content!

I picked up several batches of slides from Goodwill and on eBay out of curiosity

I am just curious, so you buy these pictures in batches form. Then you play it? Sorry I don't know much about this stuff.