Checkline TI25LTX [TI-25LTX] Ultrasonic Thickness Gauge Kit (Steel Only), 0.040-6.000" (1.00-150.0 mm) . The Checkline TI-25LTX is a simple to use wall thickness gauge is designed for measuring wall thickness and the extent of corrosion of steel. It is commonly used for checking the thickness of pipes, tanks, plates, and other objects. It is designed and built to withstand harsh industrial conditions and is backed by a 5 year limited warranty. The TI-25LTX has a fixed velocity of .2330 in/μs. / 5920 meters/sec which is the speed sound travels through common steel. It can't be adjusted for any other materials other than steel.