These control the temp of the air coming out the vents. The left controls the left three vents and the right controls the right two.
As far as how much the vents blow, I'd leave that one up to the blower motor. =D
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Kinda sorta, yeah, no?
'02 Black GTP - RIP 03/03/08 ||| '06 Black G35 MT6 - Stock ||| '73 Chevy half ton(resurrected)