» Belfry Bat Detector    Hand built to order, an assembled unit that is portable, small, lightweight and is powered by a 9 volt battery.    http://www.econvergence.net/batdet.htm

» Bertrik's bat detector page    Information on building your own bat detector    http://www.home.zonnet.nl/bertrik/bat/bat_indx.htm

» Convergence Technologies, Inc. (USA)    Bat detectors    http://home.earthlink.net/~infocentr/faq.htm

» Pettersson Elektronik AB (Sweden)    Bat detectors    http://www.batsound.com/

» Stag Electronics    Bat detectors, books and CDs of bat echolocation, downloads of bat sounds and bat music.    http://www.batbox.com/

» Ultra Sound Advice (UK)    Various ultrasound devices (air ultrasound, bat detectors, and data logger).    http://www.ultrasoundadvice.co.uk/