Call up Acme. Best props out there! 3 blades for a DD, 4 blades for a VD. Why you may ask? 4 blades gives you more transom lift which you need for a VD because the engine is in the back. A 4 blade on a DD will create more air pockets in the water causing you to loose power. The 3 blade will cut super smooth through the water giving you better bite and more power for your hole shot. Call up Acme, tell them what boat and engine you have, and how much weight you will be putting in it. They will get you the correct prop for your boat.