Stan's Universal Presta Valve Stem
Possibly the most important and most often overlooked safety equipment in a tire are the valve stems. Valves help keep the air in the tires and create an airtight seal. Stan's Presta Universal Valve stems are compatible with BST models as well as various tubeless models. Removable valve core makes adding sealant easy. Fits up to 8mm valve hole.
Have tried other brands and never got a good seal. Finally put these in, sealed first time and have had no issues. You get what you pay for.