Aside from the inclusion of a variable speed pump, the NZXT Kraken X41 improves from it's predecessor, the Kraken X40, by adding a thicker radiator with a more dense fin array which accounts for 36% more surface area. NZXT has also given the Kraken X41 extended tubing to ensure compatibility with all installation environments. Included with the Kraken X41 is a FX140 V2 PWM fan which according to NZXT is more powerful, quite, and durable than it's predecessor. Most importantly, the Kraken X41 has a 6 year warranty, which just goes to prove how confident NZXT is of the Kraken line.