Cavagna Kosan 924N RV Auto Changeover Regulator w/RV 'L' Bracket

Is this valve for high pressure or low pressure propane tanks?

How do you indicate to the changeover regulator the tank that you want to take gas first?

Is this one actually •220,000 btu capacity most i see are 160,000?

Is this regulator adjustable? I seem to be having an issue with mine and low pressure. Is the nut at the bottom an adjustment nut?