Whatman 1540-324 Filter Circles, 24mm Dia, Hardened Ashless Grade 540, 100/pk (PN:1540-324)

GR 540 2.4CM 100/PK
Quantitative Filter Papers - Hardened Ashless Grade 540 Circles, 24 mm 100/pk The general purpose hardened ashless filter paper with medium retention and flow rate. Extremely pure and strong with a hard surface. 

Also, check out the Ahlstrom 0540-1850 Quantitative Filter Paper, Grade 54, 185 mm