Garthside Pro Tip: It is a good idea to change 1-2 inch filters every three months, 4 inch filters every six months and 5 inch filters every 12 months! Your air filter definitely needs changed if it is visibly dirty and certainly if you can't see the material of the filter itself! www.penetang.com/garthside
Garthside Pro Tip: It is a good idea to change 1-2 inch filters every three months, 4 inch filters every six months and 5 inch filters every 12 months! Your air filter definitely needs changed if it is visibly dirty and certainly if you can't see the material of the filter itself! 
