Yeah you described it even further, and I generally agree. Also yes, anus itself as the muscle does feel the texture way stronger (which, btw, acts as a great reminder to lubricate very well).
Normally, the diameter is listed IIRC, and I generally understand the size of 1,75". I'm personally no size king though and go 1" as a comfort option and 1,4" when I want to feel it hard. Anything above that just feels straight uncomfortable no matter how much I relax.
I'll check Qualia out on those terms, thank you!