Stant 10511Y E85 Flex Fuel Locking Gas Cap Designed for all E85 fuel vehicles and is a deterrent to fuel theft and vandalism Stops theft of expensive fuel OEM quality construction and materials Replacing an old, leaky or missing gas cap can save as much as a gallon of gas every 15 days A new gas cap can pay for itself in less than three months. Aftermarket fuel caps are not designed to be attached to gas filler neck tethers due to the differing tethers across vehicle makes and models.