While we've seen (and reviewed) a few Bluetooth proximity alarms in our day, these guys are still pretty a much a niche product. The premise is pretty straightforward: paired with your handset, the device emits a shrill alarm on the event that the two are separated. Of course, this depends on you keeping the thing on your person, and not in the backpack or laptop bag in which your phone resides -- something that's presumably more likely to occur with the credit card-sized Blue Watchdog by Secu4 than it is with other solutions we've seen. Selling for €70 (about $95), is small enough to fit inside your wallet, and features a stand-by time of 120 hours, thanks to a 3.7 volt LiPo battery. It can be charged via recharger or USB, sports a 100 decibel alarm, and can be configured to go off if separated from your handset anywhere from one to thirty meters. On sale now from the company's website (which also has a complete list of compatible phones), but not so fast: you'll want to see it in action first, right? You're in luck! There's a video after the break.