Marine Flame arrestors are required; by law; for every boat with a gasoline engine. Holley marine flame arrestors are designed to protect your vessel from the potentially disastrous effects of backfire; plus they look great. A properly sized flame arrestor is a must to get the maximum performance from your vessel. A flame arrestor that is undersized will restrict engine breathing as would a dirty air cleaner. Holley offers aluminum; chrome and stainless steel flame arrestors in various sizes. The charts below list these by finish and also their sizes and recommended CFM. The recommended CFM column is a selection guide so that the flame arrestor could be properly sized to the carburetor s CFM capacity and existing space restrictions.