From what I know about them when helping install them in a new retail store where i was working a few years ago, there's quite a few of them that act like nothi

From what I know about them when helping install them in a new retail store where i was working a few years ago, there's quite a few of them that act like nothing more than a keyboard. the fancier ones with a display still hook up over usb and i don't think they use a challenge response (I honestly don't know there, i don't know the software for them). Even once I got them in if i was skimming I wouldn't even bother removing them ever. Instead I'd use something like the little XBee modules or some other wireless device to read them and just walk in and act like a regular shopper leaving the retrieval thing in my pocket the whole time.