The DT-1 air filters are double layered and are made of the highest quality foam. This attention allows DT-1 to offer a high-performance air filter with high airflow without sacrificing engine protection. The DT-1 air filter consists of two components, the base filter and the foam. The DT-1 air filters can be pre-oiled, even the oil used complies with the highest quality criteria, guaranteeing the filter fireproof and biodegradability.