2.Filter diameter have 13mm and 25mm two types. Filtration membrane aperture has 0.22, 0.45um 3.Membrane material has:RC, Nylon, PVDF, PTFE,etc. Choose proper membrane is very important. Aijiren Syringe Filter Features: 1. Syringe filter outside case use high qualified Health level polypropylene material (PP) 2.