Glass microfiber syringe filter. SGF syringe filters contain a glass fibre filter with a retention efficiency of 98%. It is very useful when relatively dirty solutions have to be clarified, or as a pre-filter of 0.2 μm or 0.45 μm SCA. They are available in 0.45 μm, 1.0 μm, 0.7 μm and 3 μm.