V3 UT test block is used for calibrating ultrasonic flaw detection equipment in both laboratory and on-site conditions. This block is intended to function as a more compact and light-weight alternative to V1 or IIW-Type Test Blocks. Includes 25mm, 50mm, and 100mm radii, (2) 3.0mm diameter through holes, engraved reference mark scales, and a 0.4mm wide x 2.5mm deep slot.