RAK Media brand PTFE 0.22µm syringe filter. Available in both 13mm and 25mm diameters. These autoclavable 0.22 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!
The size you should choose is personal preference. Both filters function exactly the same.