the wireless device would work on a standard wireless frequency and based on it's size it would need to be fairly close to the monitoring unit. I would assume if you lived on a long road without many places to park that the vehicle where the receiver was located would be fairly noticeable. I would immediately mark the package 'return to sender' then take the dog for a walk around the block.If you wanna go high tech I think a regular wireless detection device sold in most spy shops would work just fine. Just make sure you turn off all devices that give off a wireless signal such as your cell phone so you get the best results when trying to detect something coming from the package.If you do a search for wireless detection there is a lot out there: http://www.spytechs.com/bug_sweep_equip/Bug-Detector-SK199.htmA pen RF Detector for $50... carry it in your pocket, run it around the package before opening.TJ