Some have one, some have two. If you have a broken one, it needs to be fixed. It isnt hard to do, and Ive been in plenty of shops where an easily repaired tool is left broken, until it gets worse, or, somebody gets hurt.

jOe, why dont you concentrate on that subject you understand so well, exercise? Vise and vise mounting dont seem to be something you understand.

Jim, I havent really beat on a vise. I have a small anvil, and a 4 round of some sort of alloy steel that get used for beating on. Accurate love taps can be administered on a vise. If the mount is solid, that is all you are likely to need.

Best,
Ted