I bought these to replace the MIG tips that come standard on Harbor Freight 90-amp welders. Great little cars but Mig's advice makes it hard to see your feed. These new attachments allow you to see the start of feed so your length will be more accurate and your welds will be better as a result! I honestly can't speak to durability, but I used them on a 77" x 84" pipe. a frame with several crossbars, numerous bolts and several corner plates. and they are still going strong!