Here are a couple of options in that size. There is a wire around the top. Let me know if you don't think these are what you need.
Polypropylene:
http://www.waterfilters.net/Pentek-PO5G2S-Filter-Bags-255063_p_0-1045.html
Polypropylene High Efficiency:
http://www.waterfilters.net/Pentek-PO5HE2-Filter-Bags-255129_p_0-1097.html
Thank you,
WaterFilters.NET