If you’ve viewed the images of the Swift Box you will have noticed a metal bracket under the bottom of the nesting box, this is designed for the loudspeaker.
Swifts return to the same nesting site every year but if something happens to that site they have to look for a new location in the vicinity. In such circumstances you need to attract your first pair of swifts.
Swifts are sociable birds and are attracted to popular nesting sites where colonies are already in existence. One thing that really does work is playing their attraction calls at your box.
When you purchase the speaker it will arrive with 10m of cable and a CD of Swift Calls.