Dinex Diesel Oxidation Catalyst (DOC) Inlet for Cummins/Paccar Pancake Aftertreatment Systems is engineered for in-line EPA17 and EPA21 exhaust configurations used on Cummins X12/X15 and Paccar platforms. This compact 'pancake' style DOC integrates directly into the inlet section of the aftertreatment train to perform catalytic oxidation of exhaust constituents ahead of downstream particulate and NOx control components. The unit incorporates a metallic substrate and a Dinex proprietary catalytic coating to achieve rapid light-off and consistent conversion activity at operating temperatures typical of on-highway duty cycles. Included with the assembly are clamps and gaskets sized for direct-fit installation, and the product is offered with a multi-year warranty to support fleet uptime planning. Measurable operational value to fleets includes restoration or maintenance of oxidation activity that preserves downstream component function, reduces accumulation of soluble organic fraction on diesel particulate filters, and helps maintain exhaust temperatures required for regenerations. The compact footprint and inlet orientation are designed to fit pancake-style aftertreatment layouts, enabling straightforward replacement without extensive modification to the exhaust routing. Physical specifications published for this assembly include an approximate length of 21.41