I had my LBS convert my fat bike to tubeless when I took possession of it three months ago. To be clear, I have had no reason to complain about the Stan valves that were installed as part of the tubeless conversion. I ordered these Milkit valves after watching the company's video online and wondering about the status of my sealant. A few days ago, I switched out the Stan valves for the Swiss-designed Milkit valves, which allow you to withdraw and add sealant through the valve – importantly, WITHOUT breaking the tire bead open. I had to break the bead open on one side of the tires in order to replace the valves and did not have too much trouble re-sealing the tire onto the rim (I had to use the soapy water trick on one of the tires, which gave me an excuse to clean the wheel!). It was really easy to transfer the still clean old sealant back into the tires - through the new valves - using the provided syringe system, and I expect extracting the sealant in the future will be just as easy. The Milkit valves are shiny black and fit nicely with my black rims and black frame. I am glad I won’t have to break the tire bead again the next time I just want to check on sealant levels and add/replace sealant. I am very happy with the upgrade - so far so good!