the link is an example. also see iPlumb.tv - PEX Fittings Flair It Bulk
- the manufacturer has some good information as well - Flair-It PEX Plumbing and Radiant Heating Systems
The local TruValue hardware has some, the local RV parts store has a good collection as well.
These are re-usable PEX fittings. Some of the gator or shark byte fittings are re-usable, some will handle copper so it pays to read the packaging carefully if you get those. The Quest fittings, also commonly available, will handle both PEX and copper, too.