In honor of Google changing names from Android Market to Google Play Store, many an app or game is on sale for a fraction of it's original cost. One of them, Smart Tools, is a great app with 14 measuring devices built in. You can use this app to measure angles when sharpening. Works really good and for only $0.25 it's a must have! Act now before the price goes back up. https://play.google.com/store/apps/d...kudG9vbHMiXQ..