Nowadays AKA company provides two main types of searching coils: mono coil and DD coil. The company renews production and implementation of supposedly outdated 8 inch mono coils at the buyer’s requests.
8 inch mono coils stopped selling many years ago. They were replaced by effective DD models which were recognized not only by russian, but also by world specialists. However, buyers do not stop being interested in outdated variants for several reasons:
The first advantage-the main reason why treasure hunters support mono coil return. It provides deep search creating a cone-shaped magnetic field. Territory of any trash is accessible.
DD models are good in surface field distribution and less prone to errors in mineral soils. Also they better probe heavy soil. But when heaps of rubbish are scattered, innovative coils are powerless.