Flaw detector types are classified according to the physical principle used to locate material discontinuities, each influencing adoption rates across the application spectrum. Ultrasonic devices, employing high‑frequency sound waves, dominate the market with an estimated 35 % share due to their versatility in metals, composites, and welds. Radiographic systems, which rely on X‑ray or gamma‑ray penetration, hold about 20 % of sales, favored in thick‑section inspections where deep‑penetration imaging is essential. Electromagnetic‑acoustic (EMAT) tools, generating ultrasonic waves via electromagnetic induction, contribute 15 % and are valued for non‑contact testing on hot or moving surfaces. Eddy‑current probes, exploiting induced currents in conductive materials, represent 12 % of the market, primarily in aerospace skin and tubing examinations. Phased‑array ultrasonic units, offering electronic beam steering, capture 10 % as they enable rapid, high‑resolution scans of complex geometries. The remaining 8 % comprises emerging technologies such as guided‑wave and laser‑ultrasonic detectors, which are gaining traction in specialized niche applications.