These large, coin-shaped amulets are generally intended for hanging on houses or buildings. They are often Vietnamese in origin, rather than Chinese, though usually all lumped together as "Chinese" because they bear no mark of origin.
Such things are virtually impossible to catalogue properly, but that hasn't stopped people from trying. A classification system invented by Edgar J. Mandel in the book "Metal Charms and Amulets of China" is also used over on the zeno.ru database of "Chinese charms" and divides these charms into several dozen categories. Your smaller one, with the twelve Chinese zodiac animals on the revere, would classify as a "zodiac" charm; the larger one with the ox on the back would probably be "four characters obverse, pictorial reverse".
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis