When I first saw the HLURU K21 Kalimba, I wasn't so interested in it, becaused it seemed "too pretty" in order to be a good instrument. It seemed like some of those beautiful acrylic kalimbas which habe pictures of anime girls imprinted but end um having dead tines and so on. I thought this one would also into this style over substance category.
Was I wrong.
The K21 sounds really good. Each tine has sustain, none of them sound dull or dead. What I like particularly on this instrument is the compact shape of the body. It is more round, feels good and allows best access to the tines from all angles.
Like the HLURU K17 Flatboard it presents attributes of wooden kalimbas as the light weight but the sound has some resemblance of acrylic kalimbas as well.
It has a little weaker resonance which makes it sound not so powerful like wooden kalimbas but more sweet and delicate.
The tines are quite thin and easy to tune - unfortunately they also untune themselves a little easier, but that's not so much of a problem.
The only real downside I found was that the four lowest tines underneath the C have a strong overtones. So strong in fact that my tuning app couldn't recognize the actual undertone of the tine itself.
However, I found a way to fix this issue: I put long tine stickers onto those tines. These stickers are usually too thick and heavy and influence the resonance of the tines very strongly. In that case however it was exactly what I needed. The overtones were canceled out. It sounds lovely now.
PS.: Oh, and the instrument body looks cool as well. ;-)