Freight Train Pro Engine Add-On Kit The Freight Train w/ Pro Engine is a high-power thermal extraction heater. The heater body (or engine) is constructed of grade 2 titanium, and filled with 4mm ruby spheres. The screenless design of the engines means that these are the only two materials in the heat path of the device, making for clean and flavorful extraction. The Pro Engine provides a dry material thermal extraction experience tailored for the consummate extractionist. The modified shower head creates the least restriction possible, allowing for maximum airflow. This also means it’s easier to get overpowered by its increased throughput, which is why its recommended for professionals only! The Add-on Kit comes with a Pro Engine (on 100W coil with handle) ready to plug into your Old Head (or compatibly wired) PID.   WARNING:- High-Power Heater! Use with caution!- Exposed coil/element is extremely hot. Do NOT touch once powered on!- Do not leave unattended while powered on! Included 1 x Pro Engine 1 x coil for freight train PID