Why the iGaging AngleCube? It has a U.S.-made, solid state angle sensor that also measures absolute level in addition to relative angles... So it works like your 4ft long spirit level for straightening out cabinets, machines, and pictures on the wall, but at just 52mm square, you can carry it in your pocket.
Calibrate it at any angle, and it measures to any other angle with 0.05°resolution... perfect for setting the tilt of table saw blades or the tables on band saws and drill presses. Magnets on three sides of the sturdy aluminum case allow it to stick wherever you need it on your machinery or the side of your fridge. It uses a standard 9V battery, too, so you can find replacements anywhere (battery included).