Plastic hooks are commonly found in bathrooms and changerooms, and no one bats an eyelid. But police have warned about a particular type of hook that is far more sinister than it looks. Perverts have been purchasing hooks online with hidden cameras to install in public toilets, hotels and changing rooms to spy on people, NBC reports. If you see one, the police advise you to report it straight away. The hook devices can be purchased from eBay for between $10 and $30 - they're sold as home security devices or "nanny cams". Bidding for similar hooks were tracking at $45 on Trade Me this evening, in an auction offered by "in trade" trader usar1, listing a "Manukau City" location. The same trader had another brand available at a Buy Now price of $26, and one with a remote control trigger at a Buy Now price of of $55. The ccc-store on Trade Me in Dunedin also had a model available at a Buy Now price of $26. In-trade trader blahblahblah8 from Tauranga had a model at a Buy Now price of $26.99. These look like any other ordinary hook, but include a small dot at the top which houses a tiny 1080p camera lens. The concealed hook cameras are battery-operated with a small memory card, and can be mounted anywhere. Private investigator Carrie Kerskie told NBC advances in technology make it easy to install cameras in public places and record footage for personal use. "The battery life for these coat hooks, is two hours. Then, you just take it out, pop it in the computer, and you have all your images," she says. "It's real simple and easy. They just walk in, hang it up, walk out, go back a few hours later and take it off." The warning comes after Florida police advised the public following the discovery of the cameras in public toilets. Hidden battery-operated cameras were found in hooks in women's bathrooms at three different locations. At the time, Florida Keys sheriff Rick Ramsay told the Miami Herald anyone who had a public restroom on their property needed to check them closely. "Keep in mind, though, that these are very small cameras that can be mounted in many locations and hidden in many seemingly everyday items."