Kit includes Any form magnetic base and disc and rotor/ball joint gage. Checks ball joint wear and disc rotor run out. Magnetic base can conform to any shape or form. Checks tire and wheel run out, gear backlash, valve guide wear, etc. 12 in. flexible arm Indicator features 0-1 in. travel and .001 graduations. Magnetic base has 40lb pull. Magnetic segments conform to any odd shape. .