Plumb Bob 5th is an instrument to check if an object is perfectly vertical/plumb and has been used since the time of the ancient Egyptians. Now, we bring it to you right on your iPhone/iPod touch/iPad with Plumb Bob 5th. Professional design, maximum accuracy, different levels of sensitivity from normal to very high, it suits any types of your needs, such as: hanging pictures, carpenter work, brick layer or building construction.Features - 3D simulated plumb - Support multiple angle units: degree, radian and gradian - Easy and quick calibration function - Magnify the level reading by supporting different sensitivities (more sensitivity = small reading = subtle changes detection) - Sound follows the plumb positions for easier control and can be enabled/disabled - Lock and unlock modes - Eye catching interface - Retinal ready, just more beautiful on iPhone and iPad retina - Universal binary, download once and it also runs beautifully both on iPad and iPhone-- CALIBRATION INSTRUCTION -- 1. Put your device on a flat surface or table (its back/edge lies on the surface/table) 2. Press "calibration" button located at the upper-right of the screen To make your device work more accurately, calibrate the plumb bob before use.Visit www.skypaw.com for more information and products-- SPECIAL NOTE -- Plum Bob 5th is the 5th tool among many other professional tools in our app "Multi Measures - All in one measuring toolkit"