Update. If you redd my OP and are thinking of taking up foam rolling -- step away from the Order button and you won't get hurt! Maybe.
I ordered the wrong kind, as it turns out -- why it hurts when it's not supposed to. YMMV, but if you're a softie you'll want to learn more about the various options. My current one is medium density, 6" in diameter. Hard as hell and way too big. I'm now scoping out a "soft foam roller" of a 3" diameter. Soft might be too soft for you . . . anyway, point being selecting the right foam roller is not as simple as it seems at first.
Be warned. 🙂
ETA: An Amazon reviewer said this about the Cando-30-2103 PE White Foam Roller, 4" X 12", Round: "I've never understood traditional rollers. They're so big you kill yourself just with the effort to keep you at the same/similar level of it, plus the excruciating/amazing pain of rolling out muscles and IT bands. I'm exhausted just from propping myself up."
This reviewer, obviously quite intelligent and discerning, is named NYCReview. S/he is probably a friend of Jon's. S/he goes on:
"This size does it all. Rolls out your aches exactly as the big one does, but you can lay on the floor/mat quite comfortably and even rest as you sit on a good spot a while."
The Cando brand is sort of shaping up as possibly cheap junk. Might be an okay first purchase if you're not sure about going on with it.