Once again ThinkGeek arrives with the perfect thing that you never knew you needed until you see it. This little keychain fob with the quick-release is actually a 6-in-1 Tire Pressure Gauge Multi-Tool. It has a tire pressure gauge and color-coded depth gauge. The depth gauge can also be used as a bottle opener and a flat-head screwdriver. It also has a push-button LED flashlight that promises 100,000 hours of light. (I guess the 6th tool is the keychain quick release.) The 6-in-1 Tire Pressure Gauge Multi-Tool is $9.99, cheap enough that you can leave one in the glove compartment of each of your cars.