The Locked On Proximity Sensing Shirt is smarter than you. Thanks to an integrated radio frequency transmission/detection system it can tell when another wearer of the shirt is within 15 feet. The shirt’s radar lights up when it’s scanning for a target and when it locks on to another Proximity Shirt it lights up as “target detected”. Awesome! You will of course need at least 2 of these $19.99 shirts for it to work (unless you just like the scanning mode) and it comes in both mens and ladies sizes S-XXL. Great if you’re the type of person that gets easily lost in a crowd too.