Airing
down on the trail is great for traction but can make it hard to air
back up for the ride home. CO2 is the best choice for this as the
expansion rate is so much greater than regular air for it's volume.
This allows you to carry a smaller tank with so much more potential for
filling tires and running air tools. The regulator is a fixed pressure
and the larger 10lb & 15lb tanks come with a protective carrying
handle.