There are three versions of the First Texas 19 kHz circuit for sale at many retailers. One is based on the original Gold Bug Pro model, sold with various coil options, and includes the now discontinued Teknetics G2. There is also a basic Gold Bug version with no manual ground balance, the bottom dollar variant. The third version is a later design that added features to the Gold Bug Pro, the result being the Fisher F19. This is now also being sold with various coil options. The F19 is also a