The FURICKCUP Stubby gas lens is made in the USA. It comes with the O-ring groove cut in the threads so you can run either a glass using the o-rings, or you can remove the o-ring and use the threads with ceramic style cups. These fit all 17/18/26 and are the same lenses that are in the adapter kits.
Quality of gas lens affects performance of Argon flow. While you may use regular gas lenses, it is recommend to use genuine Furick Cup lenses.