GR161 Filter Paper Circles. 100 Circles/PK. 9.00cm diameter circles. Glass Fiber, Binderless Filter Paper. Fast filtration speed & absorbence. Weight 68g/m2, Thickness 0.32mm, Herzberg 68sec/100ml, Rapidity 100ml/min, Capillary Rise 52mm, Retention 1.1um, Frazier Air Flow 3.6cfm/ft2.