The HSE/NPL test slide contains six sets of line gratings with varying widths. This slide is designed to test the resolution of the objectives in your microscope system. Depending on the number of line gratings resolved, one can ensure a limit of detection of 0.25um.
The Band 5 version is for the UK and Europe and comes with a green certificate.
It is the case that only the red slide matches the specific description in the NIOSH/OSHA Methods, while the Green slide matches the description in the WHO (European) method. However, both the NIOSH/OSHA methods and the WHO methods require the same phase-shift, 3 degrees. In addition, both certifications were provided by the same microscope at the HSL without change in adjustment and both slides have visible and invisible blocks that bracket this desired 3-degree phase-shift.