On my only personally owned rifle that has one, I use it quite often in the field and pesting around the house with CPHP 14.3gr 22 cals. It is a 3 position dial that with these pellets gives very close to 100 fps more velocity with each progressive position. Setting 1 gives me 650 fps and is very quiet but with plenty of power and outstanding accuracy for shooting to 25 yards or a bit more. I keep it there so I can grab it to tag something out the kitchen door without bothering the neighbors or scaring anything off. Setting 2 is at 755 fps and the POI shifts up about an inch at 20 yards, fortunately dead center on the 2nd tick mark up on my Sightron 4-20x reticle at that range. No left to right shifting. Group size is tighter at 755 fps. On setting 3 it is going 860+, moving slightly higher than setting 2 and about 1/2" to the right. Groups double in size, but still acceptable since on the other two settings they are going through the same hole at 20 yds.
I try to turn it back to 1 when put the gun in the case, but sometimes I forget, which has caused a few misses on tiny targets.
