Parts from ebay are Dual Digital F/C PID Temperature Controller Control TA4-SNR with K thermocouple, it's a very cheap PID made in China with very hard to understand 2 page manual. Also used a Solid State Relay SSR-25DA 25A /250V 3-32VDC 88 to run the Brushless DC Blower Fan 12V HT-07530D12 75x75x30mm. Install the PID, SSR, and 12 volt DC transformer ( to power fan) in 6x6x4 weather proof junction box bought from Lowe's. Had the transformer laying around from old router. Used aluminum flashing and foil tape to make a transition from fan to ball valve on smoker. Also made a small flapper inside of transition that will close when fan is off. Not sure that was really needed because I metered the ball valve down to about quarter open after pit got up to temp.