Where can I get these First Aid Supplies?

I'm taking a First Aid, AED, and Professional CPR cl this semester and we need a pocket mask. Does anyone know what type of stores would supply these? Something that's not online would be best because I need it immediately. Also, I need to bring a towel? Has anyone taken a course like this? Is it just a regular towel I need to bring, or is it some type of first aid towel? Thankssss!!!!