Morakot Racing - Universal 2.5" Inch 63mm Cold Air Intake Air Bypass Valve Filter Blue A bypass valve filter helps your engine intake to have consisten air flow and prevent hydro lock. Sometimes driving under heavy rain, cold air intake often absorb moisture into the filter, having a bypass valve will prevent this problem. Made of High Quality foam Element with Stainless Steel Mesh Preventing foam from getting sucked into Engine. This item is suitable for all 2.5" Inch diameter Pipe where bypass valve will be necessary. Installation Instructions not included. Professional Installation Highly recommended.