Pre-Oiled Air Filter Yzf4 152226XAir FilterDual bonded foam design filters out even the smallest dirt particles, while allowing more airflow than two separate layer filters (flow bench proven) Twin Air filters are slightly smaller than stock, making them easier to change while increasing dead air space around the filter for better performance Flat foam sealing ring provides a secure seat against the air box, even in the worst riding conditions Twin Air dual stage filters are the