Complex sentence: Free neutrons are unstable, although having the longest half-life of any unstable sub-atomic particle by several orders of magnitude, their half-life is still only about 10 minutes, so they can be obtained only from sources that produce them freshly.
Split into simpler sentences: Free neutrons are unstable, although they have the longest half-life of any unstable sub-atomic particle by several orders of magnitude. Their half-life is still only about 10 minutes, so they can be obtained only from sources that produce them freshly.