A quick specification comparison of the two detectors. White's Goldmaster Goldmaster 24K versus White's GMT White's GMT Instruction Manual GMT Information Page White's Goldmaster 24K Advanced Guide 24K Information Page Despite similarities these two detectors have a different lineage. The GMT was part of the effort involving engineer Dave Johnson that resulted in both the GMT and MXT. The Goldmaster 24K however I am almost 100% certain is an offshoot of the MX5 pro