Specially Designed Wrenches for Removing and Replacing the Main Filter Collar as well as the Vent Cap on Aftermarket Diesel Fuel Filter Systems. 6" wrench with a unique half-moon design provide easier access to the fuel filter. High strength steel prevents the wrench from flexing while loosening stubborn filter collars. Four teeth grab the vent cap securely to prevent damage. 6" wrench works on any diesel engines found in Caterpillar CT660, CT11, CT13, CT15, Cummins, Detroit Diesel, International, Mercedes Benz, Paccar, Daimler Trucks North America, Kenworth, Mack, Navistar, Peterbilt, Thomas Built Buses and Volvo.