Many customers say it’s even better than their pricier flat irons.

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Amazon Hair Straightener
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Over the past few months, readers searching for the best hair straighteners have been following a pattern: The majority are choosing the same hot tool to style their hair to sleek perfection.

In our 2019 guide to the best hair-straightening devices, the HSI Professional Glider flat iron shines as the best seller — and InStyle readers are far from alone. The ceramic-plated device has a whopping 29,700 customer reviews on Amazon, most of which fawn over how quickly the flat iron smooths unruly hair of diverse textures.

Shoppers love the straightener’s styling capabilities in addition to its supplemental features: The device is dual voltage — meaning you can bring it on vacation to Europe — comes with a travel bag for easy packing, has a wide temperature range that the user can adjust from 140 to 410 degrees Fahrenheit, and features a clever on/off switch placement so you won’t accidentally shut off the device while using it. And while you set the specific temperature to your preferences, the iron’s floating plate structure auto-adjusts to best suit your hair thickness and type. The rounded plates are also built to avoid snagging your hair, no matter if you’re using the iron to create straight, wavy, or curled styles.

Amazon Prime Day Beauty Deals: HSI Professional Glider Flat Iron
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Shop now: $37;

Several five-star reviews even compare the affordable hot tool to CHI straighteners, long held as the gold standard in hair styling.

“This is the holy grail, guys,” one shopper wrote. “They’ve done it. They’ve made a flat iron that can control the beast (my hair) 10x better than my Chi Iron, and I can get my hair done in about 20 minutes now. FYI, I’m mixed (Black/white) with EXTREMELY thick/coarse hair. And I relax and dye it.”

Another titled her review, “Best $40 I’ve ever spent!!” She explained, “I have to start out by saying I have extremely coarse, thick, wavy, long hair and have tried many straighteners throughout the years (including CHI and other higher-end brands) and none of them even come CLOSE to this one. I've had mine for about three years now and is just as durable and works just as well as the day I bought it. It straightens perfectly, and gives a great shine to my hair as well. For someone who has issues with frizz and coarseness like me, it completely changes the texture of your hair.”

To solidify its promise of silky hair, HSI Professional includes a small bottle of argan oil with its best-selling flat iron. With so many glowing customer testimonials, $37 seems like a more-than-fair price to pay for a lifetime of only good hair days.