This is a great little device for the paranormal investigator.They are super light,compact and sensitive.They emit a static field,and anything that breaks that field will set the unit to alarm and flash.They do not need to be touched to set off and have a range of around 8 inches or so .The units are equipped with a telescopic antennae and on/off switch.These are loud and can be placed out of line of sight but still be heard.They take 1 x 9v battery ( not supplied )Please note that this is a modified item and not ‘ factory’ and the casing may have slight blemishes on them from production and packaging process overseas  ( not my modification) but that said,I take my time to make the finish very good .Having been a paranormal investigator myself for many years,I continue to use these along side my other ( very expensive! )equipment to great effect,PLEASE NOTE ,these will NOT be in packaging but wrapped in protective paper and posted in an envelope.They are a ‘base’ unit which has been purchased brand new and modified ( like a lot of paranormal equipment ) so the original packaging will not fit ,nor the original use of the item now coincide with its new paranormal use .,buy with confidence .100 % feedback and great customer service Any questions,please ask.ALSO,CHECK OUT MY CUSTOM COFFIN REMS 👀 CHEAPEST ON EBAY!👀be a little different !!