This product contains 2 silicone duck valves for use with your Spectra breast pump. Reduced suction when pumping is often the first sign that your valves need replacing. You should expect to need to replace your valves every 3 or so months if pumping regularly. The top of the valve is quite delicate and can be susceptible to fraying or tiny tears, so if you notice reduced suction or lower milk output then examine this area carefully. Your valves will last longer if you avoid cleaning them in the dishwasher.