Let me explain... I would have given 5 stars. Everything about the product was great. Quality, fit, function, etc. and the service was great also. When I bought these the first time I was just learning to tig weld and thought it would be able to let me see my arc better thus weld better, but I didn't give much thought to gas coverage.I have since started to work on understanding gas coverage and bought a stubby gas saver diffuser kit. My welds on aluminum and stainless come out much better with the latter. I think the large pyrex cups have their place and probably excell in a specific area that is not what I am usually working on. Basically what I'm suggesting is that if you are not sure of what you need these large cups for, try something else first.