Instructions for How to Use Provided PEMF Tester: For mats with the PEMF feature you can use the simple small tube tester to confirm the PEMF operation. Note: The testing vial needs to be right over the pemf copper coil to have movement in the vial therefore you need to scan the vial over the mat to find the locations of the coils. There are 6 copper coils in any mat that is 60 inches or longer. Smaller mats and the chair mats have 2 copper coils. The copper coils are connected in series therefore if one is working then they all would be working.