A simple bubble level, or spirit level, a tool used to determine the slope of a surface.

Other

Entina 2S

No

No

100%

You need 3/16ths an inch Inner Diameter x 5/16ths an inch Outer Diameter and 35mm long clear rubber tube that you can get at most hardware stores. The tube usually comes curved; you can boil a small portion while rolling it on the base of the pot or pan to straighten it out. I used Windex(R) as the spirit, it merely works, not the best as it can tend to make a lot of small bubbles if shaken. It's straight forward, you cap the tube with the end plugs and force it into the center where there are grooves the end caps retain into for grip and stability keeping the tube in the level bar.