The PTFE  Teflon syringe filter membranes are backed with an inert polypropylene membrane for support.

All the others syringe filters including Nylon, Regenerated Cellulose, Cellulose Acetate, PVDF etal do not require additional support and therefore have no additional membranes.

Click HERE for ordering information and pictures of AQ brand syringe filters

Attachment
MicroSolv Filters Equivalency  Study pdf Download File