Edge 920 welding cups are hand-made in the USA. Each cup is made out of laboratory-grade borosilicate glass, most commonly known as Pyrex. Edge welding cups are made to exacting standards and put through our quality-control system to ensure that every cup is made to fit right. Each cup is size labeled to ensure that the welder isn’t wasting time trying to find the correct size cup. Every cup is oven annealed to ensure that the life of the cup is maximized.