DDM VELOCITY STACK 3/4'' HEIGHTDDM velocity stack with 5/8" inner diameter. This adapter allows you to use aftermarket clamp-style air filters with 1 3/4" inner mounting diameter. Precision machined for smooth air flow. 3/4" height yeilds better low end power than stock. 30.5mm center to center bolt hole spacing. Dual outer grooves for sturdy clamp mounting. Fits Walbro WA / WT / WYK style carburetors. If using with a WT-style carburetor that has a butterfly choke, the center hole will need to be slightly enlarged. The "af310" v-stack is a better choice in these cases, as the center hole is wide enough to accommodate the choke plate.