Pictures are impressive and I got caught. When I received it, the story is completely different. The picture shows two rubber rings and I expected them to be top and bottom but they are not. Two pucks go to one side. The disadvantage is the possibility of air leakage. In addition, the length of the stem is short. The nut does not have enough threads to be tight. The caps are also loose. They would fall off easily. Honestly the design is good but the quality is not as impressive as the pictures.