Leg and waist joints are racheted, all clicks into place. Joints are stiff enough. Smokestacks bend to accomodate the movement of the arms. Air vents on the legs opens up when the feet are pushed up.
The only thing I can see giving in in the long run is the back area which hides the head, it is only tolerance that is keeping it stable. Possible paint chipping on the gray paint on the sides, specially when you pull it out to bring down the tires. The other thing to watch for is the joint that you push to set it back to truck or robot mode, the metal connects to plastic. Lastly you might encounter the hole in Prime's right ear, it is not a defect
With those in mind it is still the best toy I got this year, heavy, huge, and poseable. I've transformed it numerous times and still no signs of wear and tare.
Lol i see on other galleries they included 2 plastic caps... so that's what they are for...