Consistent performance whether it becomes wet or dry and most importanty does not stiffen or deteriorate with age. Diaphragm's functionality is not affected by temperature extremes. Features an inovative design highlighting robust materials like an ethanol proof membrane and a stainless steel spiral support Diaphragms provide greater reliability as variations in the molding and rubber application process have been eliminated. Rivet-free design eliminates possibility of leakage. Includes metering lever gage . Fits WT-771, 813 or 990 carbs / primer bulb type carb