Tricky to get to and only worth your time in specific situations (see Location). Tends to be more dirty than the rest of the interior of the tower, but still relatively clean. A nice beginner body crack with limited feet but solid hands.
Climb the first three pitches of Caver's, then towards the end of the tunnel crawl on P3 drop a small backpack containing the car keys and both climbers' chacos way down into the chimney below. Come through the tunnel to the open corridor, build an anchor and lower through the big crack in the floor down to the ledge. Find the backpack in the dark without a headlamp, then squeeze your way back up.
Build an anchor with large nuts and maybe a 0.75 cam in an attached flake in the open corridor.