Demagnetising the record/repaly heads removes accumulated magnetism and insures optimum signal to noise ratio. The head demagnetizer should be used every 20 hours of playing time. 
 
Demagnetising is easy and only takes a few seconds. Plug it in an arms length away from the tape heads and bring it in slowly to each head in turn. Leave for a few seconds then slowly move on to the next head. When finished slowly move an arms length away and switch off. DO NOT switch it on or off near the heads as this can lead to the head holding a magnetic "charge". 
 
TIP! A video on machine preparation, including demagging the heads, can be found on the Reel Resilience Youtube channel here: https://www.youtube.com/watch?v=gt-7nvjAPro&t=150s
 
Important! As a very strong magnetic field is generated, do not use it if you or those nearby have a pace-maker fitted.
 
Keep all magnetic recorded media (Audio-/Video cassettes, R2R tapes, Hard Disks, Floppy disks and also Credit Cards) at least 3 m from this demagnetizer when plugged in to avoid accidental cancellations.
 
This unit operates on 230 - 240 V -50 Hz - AC. 
Supplied with a 2 to 3 pin UK mains adaptor.