High performance filter for Royal Enfield; in DNA®’s Round Design.Installation of this DNA Air filter is very easy; simply follow the installation instructions included in the workshop manual.The filtering efficiency is extremely high at 98-99% filtering efficiency (ISO 5011); with 4 layers of DNA® Cotton.DNA Filter is supplied pre-oiled and The correct amount of DNA oil is applied οn each filter individually.The flow of this DNA filter is +79.07% more than the stock filter!DNA air filter’s flow: 86.04 CFM (Cubic feet per minute) @1;5"H2O corrected @ 25degrees Celsius.Stock filter’s flow: 48.05 CFM (Cubic feet per minute) @1;5"H2O corrected @ 25degrees Celsius.This DNA® filter is designed as a High Flow Air filter for ‘Road use. Note: Filtering efficiency is the amount of "dirt" the filter can maintain (stop) and protect the engine efficiently. For example the DNA® Filter for every 100 grams of dirt that it will receive; it will hold 98-99 grams; this applies even to fine dirt as small as 5 microns.