SIUI (Shantou Institute of Ultrasonic Instruments Co., Ltd.) has been making UT instruments since 1978. They are well-established, originally making flaw detectors under license from Krautkramer GmbH for the Chinese market. They are now offering their instruments to the world market.
We have visited their plant, purchased and tested their instruments and are confident in their capabilities and quality. If you compare ease-of-use, price and features, SIUI instruments are a very good value.