There are countless ways your phone can come to the rescue in an emergency, from first aid apps, to just being able to dial 999 on the spot. But if you're being attacked or pursued, you don't have time to fumble through a touchscreen UI. You need to signal for help immediately, which is easy to do with this iPhone 5 whistle case.
Called the Hoo, the case simply has a loud whistle sculpted into the back of its outer shell, with the mouthpiece hanging off the top. It's easy to use, there's no moving parts to fail, it still works if your iPhone is dead, and it protects your device. So as long as you're ok with a little plastic hanging off the top, you can get yourself a little extra peace of mind for just £20. [Hoo Whistle Case via Damn Geeky]