The diffuser in action backstage at the Jeremy Scott show. Photo: Cheryl Wischhover/Fashionista

Having covered beauty at many a New York Fashion Week, I immediately noticed something new and different while skulking around backstage during the recent fall 2015 shows: Almost every single hair stylist had some sort of squishy pouch attached to the end of his or her blowdryer. I conferred with Eliza, and she was seeing them everywhere too. Were they model mind controlling devices? Did they emit some sort of electrical shock to keep nosy onlookers from trying to talk to Kendall Jenner? I set out to try to determine what it was and why everyone was using the same thing.

It didn't take long to figure out that it was a diffuser, but when pressed for details, the backstage hair stylists were cagey. (Or annoyed by all of our hand-waving and excited chattering while they had a job to do on a tight time crunch. Hard to say.) When asked why this particular diffuser was better than a standard plastic one, we didn't get many satisfying answers. Sample real answers we received: "It's light," and "I'm not sure, but I think it's Japanese." These were generally accompanied by shrugs and the occasional side eye.

After a bit of internet sleuthing, I figured out that it's the Y.S. Park Ion Diffuser, and it is indeed from Japan. I immediately ordered one, then started emailing all the hairdressers I knew to get some more input. Here's what I learned by talking to the pros and using the thing on my own head:

Comes in two sizes. Photo: Y.S. Park

It diffuses differently. The point of a diffuser is to, as the name suggests, diffuse the hot air from your blow dryer over a larger surface area with the ultimate goal of decreasing frizz. They're ideal for keeping curls and waves intact without making them look fried and fluffy, and they can also help add volume and shine. The Y.S. Park does all this, but better, because of how it controls the heat. According to Chris Lospalluto, a celebrity hair stylist at Sally Hershberger, "Most diffusers extract heat and airflow both at the same time. This particular diffuser is the only one that extracts heat only and permits zero airflow." The titanium and silver mesh screen at the end heats up, and I can attest that there really is no airflow. It's like holding a radiator next to your head -- your hair doesn't move at all.

It stays on: I've used so-called universal diffusers before, which are supposed to slide on the end of your dryer. What often happens is that they pop off in the middle of blow drying, either whacking you in the face or clattering into the sink. My longtime hair stylist, Misty Miller at the Aveda Scott J Salon in NYC, likes the Y.S. Park because it doesn't become a projectile. "The biggest reason it rocks is the fit. Most diffusers fall off the blowdryer," she noted. "Also, it's soft. Most diffusers are hard plastic and not comfy on the head." All true, which I discovered when I used it. The adjustable bungee cord fit comfortably over the back of my dryer and stayed put.

It's light. I'm sure this is probably one of the reasons the backstage stylists love it. It feels like absolutely nothing on the blow dryer, and you can easily shove it into a purse or gym bag to travel with it to Milan or Paris or to visit your parents in New Jersey.

It works quickly. Diffusers often lengthen the amount of time it takes to dry your hair because they spread the hot air over a larger surface area and don't blow as hard. The Y.S. Park was pretty speedy. I've used it two ways over the last week: My hair has a natural wave that I've been trying to harness into cool girl waves, with varying degrees of success. I was able to dry my whole head, scrunching occasionally, in just a few minutes longer than it takes to dry it without a diffuser. The wave pattern was soft and not frizzy. I've also been using it to pre-dry. Before I blow my hair straight, I usually let it air dry for a while before I blast it with heat and attack it with a round brush. Instead I'm using the Y.S. Park diffuser to dry halfway, then I dry normally. I've noticed a huge improvement in shine and smoothness.

Price. Finally, the diffuser is not cheap. It sells for $50-$60, depending on size, on Y.S. Park's site, and I found it for anywhere from $28-$50 at various other places around Amazon. But, I think I've already gotten my money's worth out of it.

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