This air bleed kit is a must when track-tuning a Holley® 4500 DOMINATOR® or Model 4150HP™ carburetor for maximum performance. The kit includes four (4) each of the following bleed sizes: 23-41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, & 69-78. Air bleeds are contained in a plastic case that is designed to be read with the top open, keeps them separated and makes them easily accessible.