Syringe filter (13 mm diameter, 0.22 µm). Installed into a canning jar lid, the filter will keep contaminants out, while allowing for adequate gas exchange your liquid cultures. Syringe filter may be a different colour than shown in picture. Drill a 5/32″ hole in a canning lid and insert the syringe filter with the narrow end snugly into the hole. To be even more sure of an airtight fit, seal with high heat RTV silicone.