In my lifetime I have cooked 1000s of pounds of prime rib. about 250-300 weekly .
Best of all are the ones I both cooked and held in Alto Sham. Hardly any shrinkage, tender like butter and even using there directions comes out perfect every time
. I also do reheats in standard oven by wrapping rib in plastic wrap and then restaurant aluminum foil (its heavy grade ) 200 degrees about 2hours depending on rib size., also comes out perfect.