I’m a pro carpenter, have been for many years. I have C.MIV and the C.M Pro. This is all that and more, for twenty dollars! You don’t get upgrades on those other calculators and if you lose it’s gone, $80. This is great that it follows the user and not the hardware. I used the app on the job for the first time yesterday cutting in a mixed pitched roof, what a joy. I carry my phone, in an otterbox case, anyways what a great way to use it! I love my phone and I love this app!