Sharing cheap lobang on ebay and taobao for reefers looking for 4 inches & 7 inches diameter filter socks. Cost less than $4. Some even give free shipping.
http://m.ebay.com/itm/150-200-Micro...-Pre-Filter-Sock-Bag-/301791991463?nav=SEARCH
http://world.taobao.com/item/36842692862.htm?spm=a312a.7700714.0.0.U5Fny6#detail
http://world.taobao.com/item/35156402984.htm?spm=a312a.7700714.0.0.ifBRwV#detail...
Lobang sharing for sgreefers