Wheelscience TPU Nano Tubes
We just got some of these and are testing. They're about 63% lighter than our lightest butyl tube and definitely pack much smaller (for spares). So far, they feel great and were easy to install. Assuming they withstand the test of time and distance, would be a nice upgrade - even if it's just for the emergency kit. The bulk & weight difference are impressive.
C$40.00Price