This model requires 2 DPF units per truck. Diesel Particulate Filter for Detriot DD15 engine. NO CORE CHARGE. New, never re-manufactured or re-conditioned. The DPFs are tested against the OEM to ensure that back pressure, temperature, and the regeneration performance meets, or exceeds, the standards set out by the original manufacturer. This DPF is a direct fit replacements for OEM systems to ensure that installation is as quick and easy as possible. Part includes all necessary ports and attachments for sensors and are designed to operate in the exact same capacity as the original OEM part. All DPFs are backed with a 12 month warranty. See OEM numbers for direct match. ****Product cannot be sold or shipped to businesses or residents in California.**** 2 PER TRUCK.***Diesel Particulate Filters (DPF) are closed filters that remove diesel particulate mass (PM) and particulate number (PN) from exhaust gasses. Typically the regeneration process is controlled by the Engine Control Unit (ECU), which measures back pressure for the right data for regeneration. Regeneration is ensured by an exhaust temperature of around 570 - 750 degrees. The DPF use a unique mix of precious metals washcoat and substrate to turn soot into EPA acceptable exhaust.