Application: Measure the thickness of tubing and casing Detect corrosion and damage of pipe string Detect the horizontal and vertical crack, fracture and deformation of pipe string Specification : Max diameter of tested string: 12 3/4 in. (324 mm ) Min diameter of tested string: 1 15/16 in. (50 mm) Max thickness of single casing: 5/8 in. (16 mm) Max thickness of double casing in total: 1 in. (25 mm) Accuracy of thickness Single casing: 0.02in. (0.5 mm ) Double casing: 0.06in. (1.5 mm ) Min length of axial crack: 2.5" single string 1 15/16 in. (50 mm) 5" single string 2 3/4 in. (70 mm)