Maybe the best $10 I've ever spent on bike gear. I've tried every other method for adding sealant to my tubeless tires and nothing is as easy and clean. The brass adapter makes a tight seal on the valve so all the sealant goes into the tire not on the floor. Shake the bottle of sealant and squirt it directly into the injector and you don't have to worry anymore about the sealing crystals settling out and being left behind when you add sealant. Are there cheaper ways to do the job? Yes, but do yourself a favor, don't get cheap at the wrong time.