The 3rd installment in the Mason family, this particular limited run of 1,900 pieces is geared towards 2 things: advocacy and boxes. $10 from each sale from every unit sold will be split and donated to SFATA, NBS, and CASAA. Secondly, the 27mm size is perfectly matched for the majority of the newer mass produced boxes such as the RX200, Psyclone EVO, BJ BOX MODS, and the ever popularized mosfet, PWM, and unregulared Hammond boxes. The concept behind the Mason series is simple: get back to basics. There are no clever air hole patterns. No vortex or swirling air flow. No bottom or top airflow. The mason offers dual tiered, focus directed airflow straight to the coil with a continuously variable triple tiered air flow control ring. The delrin insert in the top cap is now threaded for added convenience, allowing the user to replace and remove the insert for replacement or chuff upgrades. The extended 510 connection keeps this rda safe on any mod, even if it's a hybrid. The unique heat sink built into the top cap also echoes the brick mason theme, as does the overall packaging of this rda.