These brush heads worked well as far as the actual brush head went. However, my Sonicare toothbrush stopped working properly immediately after using them. (After learning more about how the brush works, it should actually be an easy fix—but unfortunately it’s past warranty.) I believe the problem may have been that using pure bamboo as the base material for brush heads did not absorb enough of the impact of the vibration, and caused the vibrating tip of my Sonicare to become loosened as a result. This could be due to vibrating directly within the bamboo itself, but since other customers haven’t had this issue, I suspect it may be that in combination with the back of the brush hitting against my hard teeth, or the amount of pressure I use when brushing. This is all speculation of course, but I’ve had my Sonicare for several years and it worked perfectly up until the moment I used these brush heads. There are sustainable materials that would better absorb vibration, so my recommendation is to create a product that does this. Also, the silicone back of the brush head that Philips includes nicely absorbs vibration when you press the brush head against your teeth, and I found the lack of padding on the back of the brush head was uncomfortable. Relatively easy to avoid having the back of the brush touch my teeth, but wanted to note that still. The heads also fell off the brush very easily. All in all, this was not a functional product, and I wish a functional and sustainable option existed. I’m replacing my Sonicare with SURI and hoping I’ll get exactly that.