I punched the top down into the 4th First Shield for cats tube (I had used the other three), to be the third of the three recommended treatments for fleas on my cat. The tube was totally and entirely empty! I would complain on their web site asking for a refund, but I cannot find their web site. Who doesn't have a web site today? I will say that the first two treatments killed the fleas, but since a third treatment is recommended, I want to abide by that recommendation. Box is about 1 1/2 years old...I do not see a use by date on the box.