Check the listing for details. Pro Series Heatsinks for GTX, GTR. Condition: New. Listed at 79.00 USD. The new Pro Series Heatsinks for Evolve GTX, GTR are lightweight and low profile. Lightweight Weighing in at just 1.7oz (48gram) these heatsinks are designed to minimize rotating mass while increasing the surface area by 40%. Low Profile At only 58mm in diameter they will clear the Evolve Bash Gaurd and the Carbon deck even at high lean angles. Thermal Performance The outer housing of the motor has a surface velocity of 10m/s even at a typical 3500rpm's. This puts the air flow over the heatsink well within what is considered forced convection. What this means is that the rapid moving airflow over the heatsink greatly improves its efficiency and allows it to remove several Watts of thermal energy from the housing. This removal of thermal energy reduces the heat soak that can begin to rapidly increase the temperature and resistance of the copper windings at higher loads and elevated running temperatures. Interference Fit Unlike our original slip fit heatsinks, the Pro Series is an interference fit that requires that they are heated or pressed on for installation. The motors will need to be removed and an aluminum height gauge is supplied to make sure the position on the motors is perfect.