Ann: Alexium Alexicool Treated Pillows Provide Superior Cooling, page-45

From the annual report last year:
Alexium launched a new phase change material (PCM) chemistry. A blended product, containing Alexicool™, Alexiflam™ FR, anti-odor agents, binders and dye transfer resistant agents had a strong reception in the bedding market, largely in 2H2017.

You're right PCM is probably not life changing, it's a feature that the bedding industry is enjoying at the moment and Alexium was able to implement it in a cost effective way along with other necessary chemistries. It's easy to forget with the share price how Alexium went from Zero to gaining 5% (and growing) of the market share in America in so little time.