What materials to use?
Since hang tag stickers don’t need to survive harsh weather conditions, you don’t need to have waterproof materials. So most materials work. If you want my opinion, then the best would be white vinyl. That’s due to its durability.
But that all depends on your customer. If you mostly have customers that are bikers, then it would be best to make it out of tougher materials so they could put it on their helmets.