I cannot write a valid review on this vacuum check valve because it is not the one I need. A part of the '95 Buick emissions system for an LT1 motor requires two vacuum check valves in series. The smaller, in diameter, valve that I received is located near the intake manifold. The larger, in diameter, valve that I need, is located towards the distributor. Your ad features only one option for the check valve and the picture of it gives the appearance of being the larger valve. It is not. Consequently I received the smaller valve, the one I do not need. So I am out about 30 bucks.