Agate Tones are precision manufactured from the very best quality Agate. Dimensions are approx 30mm by 26mm and are 4.5mm thick tapering down to 1mm at the playing tip. Due to the hardness level of the material we have designed these to have a large playing tip area to overcome their brittleness and as a welcome side affect they have a very nice warm tone. We recommend these plectrums for precise picking on Arch Top Jazz Guitars.