Adjustment is made by turning the screw after removal of the cover. The human ear can hear only a quite high pitched note, but the dog can pick up this sound at a distance of up to 400 yards, according to the direction and strength of the wind.
During training it is important the same pitch of note is always maintained. This can be aceived by use of the locking nut fitted on the adjustment screw ensuring this does not move whilst carried in the pocket or in use.
The plastic cover will protect the whistle from dust when carried in the pocket.
