The Extech TKG250 is designed for making non-destructive measurements of wall thickness on steel structures, primarily. The TKG-250 has all of the features of TKG150 and adds Color LCD, Live waveform(A-scan), file compare, and grid review of saved readings. All models include 2oz bottle of couplant, 2 AA batteries, transducer with potted cable, and hard case. TKG250 also includes a protective holster, USB cable, and Extech XPorter software.