Newbie questions on Benjamin Kratos

Absolute newbie to PCP, just got my first rifle, a Kratos, haven't received my scope rings yet so I haven't even fired a shot. Early impression is very good, only negative I really see is the instructions could be a lot better, as an example there was a sack in the box with some spares, a couple of little discs that appear to be copper, I guess they might be over pressure burst discs but no idea where they might go. A couple different sizes of O rings, again no idea where they go, nothing in the owners manual about them, and no diagram about parts in the book or online.

One more question, on the left side of the receiver there is a small screw with numbers on it, no mention of it at all in the owner's manual so I have no idea what it does. I can take a photo if needed.
 
The screw is a power adjuster dial crank it all the way to one direction till it stops then dry fire then do opposite direction till it stops dry fire which way is louder dry fire that's the more power direction. Keep it 1/3 away from maximum power if you want best accuracy. Even 1/2 power gives good accuracy. The realistic effective accuracy is between 1/2 and 3/4 on that dial.

Those are spare seals you got. Don't need to worry until the gun needs service later on.
 
The gun is tuned to around 32fpe as it comes stock. You can shoot pellets pellets up to 30-35g weight class. My gun (Kral brand, step brothers by manufacturer) really likes the 28.5g seneca dome pellet at full power and shoots the JSB Hades reasonably well at minimum power. 

With only a slight tune, my gun is at 42fpe max and 22fpe min. The fps is nearly identical between those two pellets, and I can swap back and forth without having to re zero the scope. FWIW, the Hades work well out to 70 yards or so and the Seneca have proven well past 120 yards.

Enjoy your gun. We love photos and we are crazy about videos. Be a sport and post some!
 
The power adjuster is a knob on the right side, directly opposite of this screw, so it is probably the other end of it. I guess that this is probably an indicator for the power adjuster knob. I hadn't even noticed its relationship to the power adjuster knob. Newbies ask dumb questions LOL!

Thanks!

Yeah that's exactly what that is... and no question, is a dumb question!