Product joke. Cheap assembly, junk assembly is difficult. The lines are so tiny it's hard to see them. There are no micro numbers between steps, you have to figure it out. Not that it's difficult, but you don't have to. The price might seem right, but not if it doesn't work. If you really want to calibrate your lenses, get the Colordata SpyderLensCal. You can buy it on eBay for $50 which I did. I'm a professional photographer and I need a calibration tool that really works.