Walbro Metering Diaphram Cover $1.49 Quantity discounts available QuantityPrice Quantity: -+ SKU: AV518 ABOUT THIS PRODUCT:Walbro Metering Diaphram CoverAboutAboutWalbro metering diaphragm cover for WT / WA series carburetors without primer bulb (e.g. WT-257, etc). Walbro part # 21-158-1.