A 4 channel mono mixer with volume controls on each channel, master volume on the output.
The unit can be powered by a 9Vdc power supply (not supplied) or a 9V PP3 battery (not supplied)
To insert a battery, push inwards on the battery cradle (on the right-hand side of the unit) and slide
up to remove the battery cradle. Insert a 9V PP3 battery making sure to observe the polarity marked
on the bottom of the cradle. Re-insert the battery cradle and slide the catch
down to lock the battery compartment.