The Lighters:

Some of the lighters, tagged with their transmission
frequencies, ready for dispersal:

The main goal in our lighter design enterprise was to make our product
look as unspectacular, unsuspicious and normal as possible.
So we used proper average smallish lighters, had a plastic casing with
an extra cavity for the transmitter manufactured and just slipped them
in to make the small 'Bic' lighters look a lot like their bigger brothers.

Details on the components and their assembly can be found here.

But after all that time and money spent to achieve the perfect transmitting
lighter, we went straight on to losing them.