ADA or ADAC seating experiences?

Hey guys, Go ‘Stros! I have a guy who’s a season ticket holder and has an ADA (or ADAC?) seat ticket that he’s always selling. He told me its very spacious and they bring me a chair to sit? Im assuming these are usually used for handicapped fans? If not, are these seats any good worth it? Anyone have experiences with these seats? He’s always selling them for $20 but I also don’t want to take someones spot if im not allowed that seat.

Thanks again!