I got these two cactus and would like to know maybe what they are and how big they might get. Thanks
The first looks like it might be a Ferocactus gracilis. Their central spine is flattened, but your cacti's central spine looks rounded to me. It could be because it's a juvenile and possibly hasn't grown in intense enough sunlight. I have a F. wislizenii that, until I recently placed it in full sun, had round central spines. The gracilis species grows to somewhere around 5 feet tall and 1 foot in diameter.
The second is definitely a Mammillaria. It could be a Mammillaria formosa. If it is, your specimen looks like it is closely reaching it's maximum size.
I'm not completely sure, but from what I see, they could be those species.
I love seeing new pics of Ferocacti! Thanks!
Second looks like a mammillaria wiesinegri