Dartfreak75... Quick TQ tuning tips Video I made for you

Thank you very much that clears up alot of my questions!! Awesome video as always!!
I'm gonna be honest I didn't know what the metering rods were on a tq at all until now I didn't understand that at all lol.
I'm still 100% clear on the flap I understand how to adjust it I just dont understand they why. What does that flap do? Does it act like a choke for the secondary to keep them closed off until they are being used?