In response to a question I asked Jack Gifford 10 or 12 years ago Tesoro uses a variable oscillator, he called it a "rolling oscillator", that basically makes the coil part of the circuit that determines the frequency. That's why the same coils will work on Tesoro detectors that range from the "Lady" version of the Shadow X2 that's around 9.6 to the original Golden Sabre at 15 khz. Same for the "hot" circuit Tesoros that have frequencies from 17.6 kHz for the Tejon to 14.3 kHz for the Cibola. The Barons don't use an oscillator. They use a tank circuit to determine frequency, so it's highly unlikely a coil from other brand detectors will work unless it's modified.