It's like an invisible shield against humidity.  

Living Proof's Straight spray is made for prolonging blowouts, but it's actually a miracle for all styles. It's known for blocking out humidity—sound like something you might be interested in? Seriously, a quick spritz of this totally seals hair against moisture and prevents frizzing and limpness. I live in San Francisco, where we’re perpetually shrouded in fog. It’s nothing short of a damned miracle.