This project is the Sherlock Holmes "Case Hat", that iconic deerstalker hat with the bills on the front and back and the two ear laps on the sides. The twist here is that an ultrasonic rangefinder will be attached to the rear bill that will alert the wearer to people or objects behind them, giving them a Holmes-esque sense of situational awareness. RGB Neopixel LEDs will be sewn into the front bill that will flash various patterns depending on the readings from the rangefinder. A piezo buzzer will also be used to alert the wearer audibly if something or someone gets too close. A 500mAh LiPo rechargeable battery will power the hat, and switch will turn the hat off when not in use.