While inspecting a completed coupling with a flashlight, a driver looks into the back of the fifth wheel. What should the fifth wheel jaws be closed around?

AAMVA CDL Manual, Section 6.4.1, Step 13, p. 6-8 to 6-9

A kingpin coupling that has closed around the wrong part, or hasn't closed fully, can separate from the tractor while driving, a catastrophic failure that drops the trailer or lets it swing free. This flashlight check is the last chance to catch a bad coupling before pulling out.