PROFORM s new modular 1-2-3 Series Radiators and Accessories fit together just like they should, nice and easy! Start with this 23 wide core Stage 1 Radiator, part no. 123G000 as the foundation for your cooling system. These aren t just your ordinary single pass radiators, they offer beautifully tig-welded tanks, and a slick profile thanks to PROFORM s unique Four-Corner Design. The Four-Corner Design makes it easy to attach the exact fit Stage 2 Fan Shroud, part no. 1231S00, because the mounting holes line up, making installation a breeze with the included hardware. For the ultimate professional look at DIY costs, take the 1-2-3 Series Stage 3 fan, part no. 67016 or 67027, and mount it up to the pre-threaded holes in the shroud; then top it off with a fan controller to make life easy. It s easy as 1-2-3! This is a really nice cooling system that's ready for the show, streets, or strip! This Stage 1 Radiator has dual one-inch tubes, single pass, with optimized louver design to maximize cooling, and deep draw headers for an extra solid tube/header seal. Billet aluminum filler neck with overflow tube, and a billet aluminum 16 psi cap are included. No epoxy or anything else like that just tight tolerances all around. Building your custom cooling system is easy!