Google "guru" or "stoker" and get comfy, lots of info out there.
What? Electronic devices that regulate air intake into a smoker to keeps temps consistent.
How? They all work different depending on the cooker it is designed for. Usually a thermostat regulated fan that kicks on off.
Dampers? Again it all depends on the cooker. Too many variables. Some you might need to mod others use designed for specific cookers, like the BGE.
Just make sure they are plugged in right before using them. (Wood Chicks Mod)