Standard Glass Bead Reference Materials for use with ASTM testing sieves. These items are calibrated glass beads for determining effective sieve openings in test sieves and not for determining whether the sieve conforms to specifications.
| Part Number & Name |
| HN-3950 Glass Beads, NIST Reference – No. 10 – 20 (2450 to 750 micron) |
| HN-3952 Glass Beads, NIST Reference – No. 45 – 140 (4000 –100 micron) |
| HN-3954 Glass Beads, NIST Reference – No. 400 – 635 (38 –20 micron) |
| HN-3955 Glass Beads, NIST Reference – No. 30 – 635 (600 –45 micron) |
