The MCR420-QP (Quiet Power) is an extreme-duty liquid-to-air heat exchanger designed to be used with four 120mm fans, and specifically engineered for high-end liquid cooled Personal Computers. The Quiet Power technology is the result of months of research and development focused on optimizing thermal performance and audible noise characteristics with low to medium airflow types of fans. The MCR420-QP series heat exchangers have been engineered to meet today's PC industry highest thermal loads, quality standards, and low noise requirements at competitive prices. MCR420-QP: The "classic" form factor features inlet and outlet ports located at the top of the radiator. Features: Quad 120mm fan form factor quadruples the surface area available for convection of the heat into the air compared to single 120mm fan designs. The Quiet Power design yields superior performance at low noise levels compared to competing products in the same class. Flat brass tubes and copper louvered fins, with brass plenum chambers and frame construction, for optimum thermal conductivity. Flat frame surface provides optimum seal to the fans. Optimized for 120mm fans with low to medium air output. The added heat dissipation capacity enables multiple high-end devices (multi-core CPU's, and SLI systems) to run highly overclocked at the lowest possible noise levels. Fin density optimized to reduce air noise. Built-in plenum chamber. 1/4" NPSM threaded hubs (BSPP and G1/4 compatible) for maximum compatibility with various tubing installations. Self purging plenum chambers design: when installed upright or on its side, air cannot accumulate in the plenum chambers. Threaded fan and case mounting holes for quick and repeated installations. Slim design to facilitate installation & reduce bulk. No oxidation over time (compared to aluminum radiators). Beautiful and durable gloss acrylic paint finish & ROHS compliant.