Alpha Nanotech Borosilicate Solid Glass Beads (4 mm, 0.5 kg / 1.1 lb)

Works well for protein extraction

Quality beads, but giving 3 stars because they don’t meet the claims in the description. I put a small handful of the 6mm beads in a flat-bottomed bowl and gently tipped the bowl to roll them around. It didn’t take long to spot a few beads that would stop moving while the rest continued to roll around (not what I would call “high-precision”). Most of the beads appeared to be free of flaws, but I did notice several with cloudy spots or scratches on their surface (not exactly flawless). There was one broken bead in the handful.

great product, fully satisfied!