Fit this over your Twin Air filter when your riding in severe conditions such as heavy dust and sand. This coarse foam pre-filter will act as an additional layer of protection. Extends the service time between filter cleanings. Designed for use with Twin Air filters. Fits: KTM 125 EXC 12-13, 125 SX 11-13, 144 SX 11-13, 150 SX/XC 11-13, 200 EXC/XC-W 12-13, 250 EXC 2-strk 12-13, 250 EXC-F 4strk 12-13, 250 SX/SXS-F 11-13, 250 SX/XC/XC-W 2-strk 11-13, 250 XC-F/XCF-W 12-13, 300 XC/XC-W 2-stroke 11-13, 350 SX/SXS-F/EXC-F/XC-F/XCF-W 11-13, 450 SX-F/SXS 2013, 450 SX-F/SXS-F/EXC/SMR/XC-W 11-12, 500 EXC/XC-W 12-13, 85 SX/XC 2013. Fits: KTM 85 SX/XC 2013, 125 EXC 12-13, 125/144/150 SX 11-13, 200 EXC/XC-W 12-13, 250 EXC/EXC-F/XC-F/XCF-W 12-13, 250 SX/SXS-F/XC/XC-W 11-13, 300 XC/XC-W 2T 11-13, 350 SX/SXS-F/EXC-F/XC-F/XCF-W 11-13, 450 SX-F/SXS-F/EXC/SMR/XC-W 11-12 + more.