Just purchased 2 HOG second stages: Can someone explain?

[Bamabowtie]

I just purchased a HOG reg set from DRIS and it finally arrived today. This is my first reg set and everything I have used to this point has been rental gear. With that said, I have never used a 2nd stage that had adjustment knobs. Can someone explain the function of the circular knob and the red lever that is on the regulator? Thanks!

 

[JBRES1]

The HOG second stage has a pre dive and dive lever on its side, and an adjustment knob there also.
The pre dive / dive lever is there to give you a directed air flow towards the diver.
Scubapro calls it the venturi lever. When it it in the dive position there is a higher flow of air going into the divers mouth.
The adjustment knob is there to allow the diver to adjust the cracking pressure either up or down. If you adjust the cracking pressure up, it is harder to breathe. If you adjust it down, it is easier to breathe, but could also make the reg free flow.
I adjust my regs on the light side, just a little above free flow when I put the reg into the water with the mouth piece facing up. I then turn the knob a little higher to make sure it doesn't free flow.

Jim Breslin

 

[tbone1004]

I can never notice a difference on the pre dive lever. I leave my primary on + and octo on - as is does seem to limit free flow. Now in Sidemount it doesn't matter, but on backmount it would. I also leave the cracking pressure all the way up and backed off a quarter of a turn for the o-rings on my octo and do something similar to Jim, however I don't allow it to free flow. Start with it turned all the way up then back it off until it's comfortable