They are made from the highest grade power flow filtering material and there's no need for re-jetting after installation. They are designed to have the same flow properties as the original air filter. The HifloFiltro air filters are designed to fit into the original bike air box and require no modification. Unlike foam element filters, the mesh road bike filters do not need to be pre-oiled. They are fully ready to install and should last 6-8000 kms depending on the air conditions. They do have some off road applications and these do require being pre-oiled and cleaned periodically.