OMG. Finally a Presta valve adapter that works great! I wish I had had these years ago. I use mine on a JACO FlowPro digital tire inflator with gauge - 200psi. I simply removed the included Schrader adapter and screwed in the Presta adapter (by hand, no air leaks). Works absolutely perfectly! I have perfect tire pressure. The Schrader fit requires me to use adapters on my bike tires which made it difficult to get the correct pressure reading due to air leaks. The Presta adapter worked with no air loss. I really like these adapters! If you ride bikes and have Presta valves this is a must! Thank you JACO!