The doors of the presidential state car have no keyholes; the ability to open the passenger doors on the limousine is a secret known only to the Secret Service.[12] It has more 5-inch (130 mm)-thick[13] bulletproof glass than the previous model, run-flat tires, and an interior that's 100% sealed to protect the occupants in the event of a chemical attack.[14] The current presidential state car boasts rocket-propelled grenades,[13] night vision optics, a tear gas cannon, on-board oxygen tanks, an armored fuel tank filled with foam to prevent explosion, pump-action shotguns, and bottles of the president's blood.[1] The current presidential state car can also fire "multi-spectrum infrared smoke grenades as a counter-measure to a rocket-propelled grenade attack or anti-tank missiles."[12] The car features 8-inch (200 mm)-thick doors. Car enthusiasts have decried the car's styling. General Motors spokeswoman Joanne K. Krell said of the new presidential state car, "The presidential vehicle is built to precise and special specifications, undergoes extreme testing and development, and also incorporates many of the top aspects of Cadillac's 'regular' cars -- such as signature design, hand-cut-and-sewn interiors, etc."[9]