2 TPU presta valve (60mm) tubes. After testing some different tubes, these are the brand I like for their quality and performance.

1/4 of the folded size and weight of butyl.  One of these on each wheel and 2 in your back pocket and you are saving 1/2 a KG in weight.  It's the most cost effective significant weight reduction out there.

Larger tube diameter to fit wider tyres (20-32mm) and retains air better than lighter tubes with more puncture resistance.

Suitable for both rim and disc brakes.

Metal valves rather than poor quality plastic which often fail or leak air

38 grams including dust caps and washer Valve length is 60mm so good for up to 50mm deep rims.

When installing, inflate the tube before inserting but only enough to give it some shape (5 PSI max). Fit the tyre as normal and as with butyl avoid using tyre lever when fitting to at avoid pinch flats. Includes 2 repair patches for each tube and isopropyl alcohol swabs for prepping the area in the event of a puncture.