There are blue white color fabric, green white color fabric, glue spunbond fabric, non glue spunbond fabric, lustring fabric. All are processed by origin cotton which are with workmanship of spray color, gum dipping, lustring etc. They have good comparability in filtration performance and function. These workmanship could extend use life, which is easy to distinguish air intake side and air-out side. Preliminary efficient fabric has good hand feeling and no rough feeling. Common thickness is 5-25mm. Non standard specification is customized.