MS1 (Equiv. to Whatman No.4) - Fast Filter Paper (20 micron) - Retention: Coarse Precipitates

MS2 (Equiv. to Whatman No.1) - Medium Filter Paper ( 5-10 micron) - Retention: Medium Crystaline
MS3 (Equiv. to Whatman No. 2) - Medium to Slow Flow Rate ( 5 - 8 micron) - Retention: Fine Precipitates
MS4 (Equiv. to Whatman No.6) - Slow Filter Paper(< 5 micron) - Retention: Fine Crystaline

Economy, G/ Purpose, No.1 - Medium Speed Filter Paper ( 5-10 micron)