Oh my goodness! This might be my favorite Kaiko purchase I've made so far (I'm building quite a collection).
I'm a pain-stimmer but I've discovered through trial and error that fine sharp textures (like the spikey hand roller) are not it for me. These larger, rounder spikes on the massage roller are exactly what I need. Very relaxing and grounding, and great for sore muscles as well.
The peanut shaped roller has different shaped spikes which is nice for delivering a different sensation. While the round roller has small cone shaped spikes, the peanut roller has long, thinner spikes which are much more intense.