The exit sign emergency light hidden cameras we offer come in 3 different varieties. Self contained, wireless, and hard-wired. The self contained DVR records to itself--it does not require any external recording device. You play back recorded footage on your computer. The wireless and hard-wired versions require external recording devices (TV, VCR, DVR). The wireless transmits the video wirelessly whereas the hard-wired version has a video cable coming out.