This is Best Level tool. (Bubble Level, Spirit Level, Water Level, Circular Level, Slope measurement)
Spirit Level with Bubble Level.
It is very accuracy level tool.
and you can Calibrate value, if you want.
This Level Measuring tools work by Smartphones level sensor.
This is a necessary tool for interior decoration. or necessary tool for a field of construction work.
also It was designed LandScape display!
You can use conveniently.
It is wonderful Slope measurement tool.
Thank you