A pretty common American model 3600 with a not-so-common Schlage Everest core.  At first I was a bit worried because the actuator didn’t seem to be working right, turning an extra 1/4 turn before unlocking the shackle.  It worked every time though, so I gave it a whirl.  The Schlage Everest really isn’t a “high security” cylinder, but if you don’t realize the bottom detent button is there and know how to defeat it, it can kick your a$$.  The lock, although called a challenge lock, really contained stock pins so I used this as a chance to show the pin, how it works, and how to best defeat it.

No giveaway this time as the owner wanted it back.  Sorry.