I still have a Fisher m-scope vlf 441 in the shed it has an 8ins 12ins and 3ins coils I got it in 1982 I have not used for years, the wife found gold with it using the 3ins coil, before I retired I would lend it out to people at work to check for water pipes phone cables ext it worked great at this with the 12ins coil and was easy to tune. kris