UNI Filter entered the scene of performance air filters in 1971 with polyurethane foam as the filtration media due to its superior dirt captureing abilities, which are particularly superior under grueling off-road conditions that include silt, dust and dirt. UNI air filters introduced the patented seamless "SOCK" filter for motorcycles, dirt bikes, ATVs, UTVs, dual sport motorcycles, street bikes and small engines in 1973 and earned heroic success amid the automotive industry. The dependable high air flow filter then became the top choice of dirt bike and ATV manufacturers throughout the world for its performance advantages.