NO TOIL manufactures the world's best 2-stage foam air filters. Using only the best flame-laminated dual-layer foam bonded with the highest quality glue they hand make each foam filter to stand up to the roughest and toughest riding or terrain. NO TOIL filters can be used with NO TOIL biodegradable clean in water cleaner providing the best air filtration system in the world. Fits: Honda TRX300 2WD FOURTRAX 1988-1989 TRX300 4WD FOURTRAX 1988-1991