The EM1A megaphone is standard equipment on Boeing aircraft where it is stowed away as part of the aircraft's emergency equipment. As a piece of SEP equipment it is there for use in the event of an emergency but apart from routine maintenance checks, is not used day-to-day by the flight attendants in the cabin.
However the same cannot be said for in the training environment where air crew are required to familiarise themselves with the ACR megaphones operation. The EM1A features a volume control and siren; both of which are used in training.
As a result of this increased used the volume control knob on the EM1A can be loose or lost, which means that crew cannot be effectively trained (completely) on the use of the megaphone. A simple solution is to have a pack of these EM1A style volume control knobs to replace any lost in training. They simply slide into place and the ACR megaphone is back to training. No tools are required!
Please note these items are representative of the manufacturers original item and as such cannot be used where operational megaphones are being made serviceable for flight operations.