Conclusion Front: shit. I couldn't complete my usual penalty run in the evening because of a flat tire in these unworthy caps. Whoever the CCP engineer is that created these things is clearly lacking in skill. The rubber O-ring, which is only there to prevent dust and moisture from entering the valve stem, is small in diameter. This causes the o-ring to slip into the valve core area and in some cases (like I've had) lightly presses on the valve. An O-ring is sandwiched between the inside of the cap and the valve stem core, slowly deflating your awesome tires (my skull and crossbones sidewalls ended up looking like cute old men gathered around a round table). The plastic is cheap, crappy and after a few days in the sun it looks like a no brainer. Any other punishment product will only get better looking with age and will only fill a hoop with your opponents tears. I threw them into a local barrel to burn the next night.