Dewalt Torpedo Level
The DEWALT DWHT43003 Torpedo level features rare earth magnets and a V-Groove base for use on metal and rounded surfaces. Accurate to within 0.0005 inches, which means those pictures are definitely going to be hung straight! 9" x 1.9" x 0.9" and magnetic, to help you when your third arm is busy.
Retail value: $20