The Power Lock is a well-built contraption that precludes the pesky Air Arms power adjuster from moving. Take the time to fit this so that it does not scrape your stock and fits easily over the adjustment wheel. My 510 is set-up to shoot either the light or heavy in .177 which necessitates different power adjuster setting to shoot either pellet at their preferred 900 fps. The different settings are ensured by the left side hash mark positions being known to me.
My only complaint is that I have to remove the power lock (easily done when fitted correctly) to move the power adjuster. This could be remedied by putting a slot on the right side power adjuster for a screwdriver, then loosening the grub screw, make adjustment, then snug the grub screw back up. The grub-screw works well at cinching the pa to the power lock.
See here for pic. http://www.network54.com/Forum/79537/thread/1340580914/Att-+AA+410+%26amp%3B+510+owners