I attached a pic of the air filter on the ISB 305 if anyone is interested. It has specs for the filter printed on it. Notice no foam on this one. If anyone can't read, here are the specs:
Dust Cap 275 G
Max Air Flow 19. 12 m3/min
Eff 98%
Pressure loss @ max flow . 035 bar
Dust Cap 275 G
Max Air Flow 19. 12 m3/min
Eff 98%
Pressure loss @ max flow . 035 bar