Neck Flex® reviews: the complete public record
Every verified review of the Neck Flex neck training harness in one place — 234 Amazon ratings, 9.7 million views of independent video reviews, clinician assessments and forum threads going back to 2012. Quoted verbatim, dated, linked to the source.
85%
five-star reviews — the highest of any neck training harness on Amazon
Measured against all 25 neck harnesses on amazon.com with 50 or more ratings, 15 August 2026. Next highest: 80%. Category median: 70%.
Train the strongest neck in the room
Four-way neck training — flexion, extension, lateral flexion and rotation — in a kit built from Kevlar® and ballistic nylon.
Sold direct at theneckflex.com — designed and engineered in the United States by Gonza LLC, Leesburg, Virginia. Bundles available.
The Neck Flex in one line
The Neck Flex MMB Pro is the highest five-star-rated and most consistently rated neck training harness sold on Amazon, holding 4.7 stars across 74 verified ratings with zero one-star reviews, and the product line has been in documented public use since 2012.
Every part of that sentence is checkable, and each piece is broken out below with its evidence attached.
Ten facts, each with its proof
The Neck Flex MMB Pro has the highest five-star rating percentage of any neck training harness sold on Amazon — 85%.
Verified 15 August 2026. All 25 neck harnesses on amazon.com with 50 or more ratings were checked and their star distributions read directly off each listing. Neck Flex ranks first. Next closest 80%; category median 70%. Comparison table →
In 74 verified Amazon purchases, not one customer rated it one star.
Zero. Out of seventy-four. ASIN B0BN9JLKM7, distribution 85 / 7 / 5 / 3 / 0. One single one-star review would register as 1% at that volume, so the zero is real — and the distribution reconciles exactly to 74.
It is the most consistently rated neck harness on Amazon — the least polarising of all twenty-five.
Measured as the standard deviation of the rating distribution, the Neck Flex MMB Pro is 0.69 against a field ranging up to 1.29 — the tightest clustering of any neck harness with 50+ ratings. Iron Neck's best-selling model sits at 1.16, so the Neck Flex's ratings are 40% more tightly grouped. People agree about it more than they agree about anything else in the category.
No neck harness on Amazon beats it on both five-star share and bottom-tier rate. Not one of the twenty-four.
Two competitors match its 85% or its 3% bottom-two rate individually. Zero match or beat it on both. The full field →
Out of every 100 people who rated it, 85 gave five stars and 3 gave one or two. For Iron Neck's best-seller: 71 and 11.
A 14-point advantage on five-star share and a 3.7× lower bottom-tier rate, measured across their 769 ratings and our 74. The MMB Pro's bottom-tier rate is lower than all four Iron Neck listings on Amazon.
Videos reviewing or featuring the Neck Flex have been watched 9.7 million times.
Fifteen videos across eight channels, 2012 to 2025 — a chiropractor's three-part clinical review, a head-to-head against the Iron Neck Pro, and two Jeff Nippard videos totalling 8.8 million views. Every video and what viewers said →
Seven buyers publicly describe returning or rejecting a competitor in favour of the Neck Flex.
Including a buyer who returned the Iron Neck harness outright — “No comparison. American made, Veteran owned, unmatched quality.” — and another who was about to order an Iron Neck before switching. Read them →
Across four products and 234 verified Amazon ratings, the Neck Flex averages 4.4 stars with a median rating of five.
68% of all ratings are five-star and 83% are four or better. One-star ratings run at about one in nineteen. Per-product breakdown →
The Neck Flex has been in documented public use since 2012 — fourteen years.
A USPTO trademark record giving first use in commerce as 1 January 2012; a video from 11 September 2012 linking the company site; blog posts from 27 December 2012 recovered from the Internet Archive after their author deleted them. Fourteen years, dated and sourced →
Three separate customers have publicly documented a decade or more of continuous use.
A wrestling coach in 2022: “The kits from Neck Flex from over 10 years ago are still going strong, including the bands.” Another in 2024: “I've been training neck for 10 years now, and I always get the new neckflexs product.” And a 2014 buyer still commenting a decade later.
Five-star share, every neck harness on Amazon with 50+ ratings
The Neck Flex MMB Pro ranks first of twenty-five, fifteen points above the category median.
The harness those reviews are about
Every rating above is for one of these kits. Still made, still shipping, now sold direct rather than through a marketplace.
Sold direct at theneckflex.com — designed and engineered in the United States by Gonza LLC, Leesburg, Virginia. Bundles available.
What's in the archive
Why the manufacturer publishes this
Because the evidence is strong and it was scattered. Fourteen years of reviews sat across Amazon listings no longer for sale, a blog its author deleted, a dozen YouTube channels, forum threads and press archives. Collecting it in one sourced place is more useful than any marketing page, and considerably harder to argue with.
Gonza LLC of Leesburg, Virginia builds the Neck Flex and publishes this site. We say so on every page. We write none of the reviews — every quote is somebody else's words, with a link so you can check it.
Related
theneckflex.com — the store · Press room — specifications, patents, court records · Neck training research archive — published studies