The Volvo And Mack D13 And D11 Diesel Oxidation Catalyst is a highly practical and efficient solution for reducing emissions in Volvo and Mack models. With a 14-inch diameter and 15.7-inch height, this catalyst is made with high-quality materials such as silicon carbide substrate and stainless steel canister. Each purchase includes 1 DOC catalyst, 2 gaskets, and 2 clamps. Please note that this product is not CARB compliant and cannot be sold in California. Compatible with OEM and aftermarket numbers 21212405, 21756505, C0097ID, and C0097-ID, this catalyst is a reliable choice for emission control.