Order 10 MSR fuel bottle caps with O-rings. They work great (though after-market), seem to be the same high quality as the "real" MSR originals. Made of the same tough nylon plastic material, fit and function is perfect. Supply Cache's copies are Gray colored, and cost $1.50. The original MSR non-child proof cap is Black colored, and the best price out there is $6.50, and often go for $12.00. For me that was a $50 savings over the next best price on the internet. Service was good, shipping was fine (not next day, but reasonable). Overall, very happy. These seem to perform flawlessly, and I would recommend them to anyone for camping or backpacking, or any fire dept, or hot shot team.