FOAM AIR FILTERS: NO TOIL manufactures the World's best 2-stage foam airfilters. Using only the best flame-laminated dual-layer foam bonded withthe highest quality glue they hand make each foam filter to stand up to theroughest and toughest of any style of riding or terrain. These filters,used with No-Toil foam filter oil, provide the best air filtration systemin the world! (Remember: NO TOIL oil washes clean in water and is 100%biodegradable; dirty water can be thrown down the sink. You do not need touse harmful petrol or kerosene to clean your filter. No Toil oil is 100%waterproof - until water is mixed with No Toil cleaning crystals).