Tectonic TEAX32C30-4/B 32mm Balanced Exciter 4 Ohms

I use these to generate remotely triggered "Ghostly Sounds" to supplement the experience of Paranormal Investigators when they go into Olde Towne Fredericksburg's "Most Haunted Sites." I don't want them to be dissappointed by their experience you see... anyway... takign some verbage in the auditory range and using a computer (Audacity) to push it up to nearly the end high range of human hearing (16KHz or above) I can create some "ultrasound" EVPs (electronic voice phenomena) as well and will play through windows and dense objects such as AC/Heating steel ventilation systems.