Available in both 13mm and 25mm diameters. These autoclavable 0.22 µm micron syringe filters are made out of a hydrophobic PTFE and are 100% reusable. They are perfect for inserting into liquid culture jar lids to provide contaminant-free gas exchange. Compare to much more expensive Whatman brand filters... the only difference is the price! These filters fit into a 5/32" hole.
The size you should choose is personal preference. Both filters function exactly the same.