Notches for UT (Ultrasonic Testing) calibration are precisely machined reference features used to ensure the accuracy and reliability of ultrasonic testing equipment. Made from high-strength materials like steel, aluminum, or specialized alloys, these notches act as calibration standards for measuring sound wave propagation. They are critical in industries such as aerospace, automotive, construction, and oil and gas. Various types include side-drilled holes, grooves, or flat-bottom holes, tailored to specific testing requirements. These notches come in defined dimensions to support effective, accurate ultrasonic inspections across materials and applications.