Calibration Beads (Borosilicate Soda Lime Glass) for Forward Scattering Spectrometer Probe (FSSP) and Cloud Droplet Probe (CDP) can be order from Thermoscientific (
www.thermoscientific.com/) or Whitehouse Scientific (
www.whitehousescientific.com). Smaller amounts are available from Whitehouse Scientific. For CDP beads from Thermoscientific use the 9000 series, see
https://www.thermofisher.com/order/catalog/product/9002. Duke Standards* 4000 Series Monosized Particles can be obtained from Thermoscientific for Calibration of the Passive Cavity Aerosol Spectrometer Probe (PCASP).