This one looks like what I already have, with that painful bit curving on the back of my head. It's unclear whether this one relies mostly on that strap or does have the painful hard piece (with slight cushioning) in back as well.
I also need to replace my tubing. Perhaps not at the same time, though. The mask is the first step.
I am so thankful for everyone who helped with this purchase. It is sorely needed! Maybe my neck will improve when I'm not tilting it to avoid the pain of the back of my mask! (I used to be a side sleeper but for other reasons that became painful.)