Note the so called plasticizers are in fact usually known as Phthalate plasticizers. This is known as attempting to keep an explanation simple, not complicated. Being a Chem teacher that is something to know.
I notice that some sites sell them for $1+ and some for only .65 cents. Both have rings. Is there something different between the two that we should watch out for or is one just a better deal?
I like 2X2's, stapled, pinch the staples flat with pliers. Remove coins from 2X2's by cutting the "window" with a scalpel or X-acto knife.