Product Details: The Donaldson Restriction Gauge Kit is in the filter, allowing for quick and easy maintenance. The kit includes a gauge, a hose and a fitting to connect to the filter. The gauge is easy to read and provides an accurate reading of the filter's restriction level. It is a great tool for any business or individual looking to maximize the lifespan of their air filters and save money in the long run. FleetPride is your First Click in Heavy Duty®.