Spray Nozzle Lawn Upgrade Kit

I purchased this for my 10L 414 to upgrade the stock nozzle which was a cone pattern. The only issue I had was, being new to spraying I had no idea which nozzle was which! I also didn’t know the purpose of the knob. It would be great if there were some instructions. Through trying it though, I came to learn that the longer nozzle (the red piece to the right in the product image) of the nozzle is the air induction one, meaning bigger droplets which are better for reaching the soil and the other one (to the left in the product image) is the fan nozzle (even thought both are fan pattern) which sprays finer droplets for folar sprays. I’ve used both and am very happy with them! Still not sure if the purpose of the knob, I thought it was for letting air in but I think it might be for removing blockages as it leaks if you unscrew it. Please add some instructions on the site for fellow noobs! I can’t even google it because there’s no brand name.