chips. I can send 3 chips (up to 3.5ozs) in a regular sized 6 1/2"x3 5/8" Envelope w/Cohesive Corrigated Wrap (Cardboard) and a $.58 cent stamp. It's a "Non-machinable" letter. I've sent many Hundreds, since last summer and only these 2 came back, both were bound for IL. curious....
here is one of them...see Scan below