Descriptions taken from Polysciences, Inc. LifeSciences Catalog 2000-2001

For Light Microscopy:

• Type A: viscosity 150 centistokes - for short focus objectives
• Type B: viscosity 1250 centistokes - for greater gap dimension
• Type NVH: viscosity 21,000 centistokes - for horizontal, inverted, or inclined instruments

For Fluorescence Microscopy

• Type DF: highest resolution, but slight green range background
• Type FF: virtually no background fluorescence