Bubble Level is a level tool that is part of the iMetalBox app and is now available for free on the iPhone. This tool is designed to help you with picture frame alignment, measuring angles and slopes, home decoration, and much more. It has full retina display support for both iPhone 4 and iPhone 5.

Bubble Level is a simple and easy-to-use tool that does not require any drama. It has received positive reviews from users who have found it to be a great tool for their needs. It is stylish and functional, with no unnecessary features.

To calibrate the levels, hold the phone against a reference surface and press the Calibrate button. You need to do this twice for vertical and horizontal orientations. Bubble Level is a great tool for those who need an accurate leveling tool for their iPhone.