In you are plagued by punctures (or don't want to be) these tubes are magic. Sealing just about any holes, so you don't have to spend your riding time on your knees in the mud, fixing punctures. If we aren't running tubeless tyres, we're running these tubes. Many group rides will insist on them or similar as otherwise the ride would just be too slow waiting for all the punctures. The big fat Schrader valves need big holes in your wheel rims or they won't fit! You can (very carefully) drill them to make them big enough though if needed. We find these valves more sturdy and less likely to gunk up.

The skinny Presta valve will fit all tyre rim holes, but make sure you open them regularly to stop them ‘gunking up’.