what type of shifts

what type of shifts are available at most prisons, 3 - 12's? 4 - 10's? or 5 - 8's?
2-8hr and 2-12hr where I am at.

Three 12's at the local jail I was offered a job at...couldn't accept the position due to the lousy benefits, though it would have been nice to have half the commute I have now