Most folks are aware of a long-standing problem with Cessna singles where the seat track latches occasionally disengage as the airplane rotates for takeoff, causing the pilot to slide somewhere into the vicinity of the back seat. It doesn't take much imagination to understand that this can be a Very Bad Thing.
Cessna has engineered an auxiliary seat stop mechanism to ameliorate this problem, and N631S is in the shop having the solution installed on the pilot's side, with Cessna picking up the bill. (If I wanted the same mod on the co-pilot's side that would be on me.) Here's a photo:
You're looking at the seat upside down on the bench, forward to the top of the picture. A webbed belt on a reel is attached to the main aft cross-piece with a pawl-and-ratchet mechanism visible at the right. The end of the belt has a fitting that will be bolted to the floor of the cabin. The flexible cable gets connected to the bale that operates the original latch mechanism (which remains in place) so that when you lift the bale you release both the main and the auxiliary latches.
It seems to be well engineered and there have been, so far, few reports of difficulties in the field. Looks like a good solution to a real problem.