Hi-Flow Air Filter (2 Pcs) 13mm HOLE SILICON RUBBER WILL STRETCH LARGER.CARE AND MAINTENANCESaturate all the foam element with special air filter oil, Do not use the airfilter dry. Take care the filter is complete coverage with oil, after cleanexcess oil with a cloth.Do not wash and re-use the foam. All dirt and dust particles are caught on the surface. East time a particle is caught, it stops up a hole. When you wash the foam, dirt particle will go into the foam. It will go intothe engine and shorten its life.Your must replace your air filter every 3/5 hours of engine use.Now, you are ready to install the finest air filter.