Real vs. Replica: GS Factory Longines Master Big Mouth “True Motion Display” L2.666.4.78.6 Watch Comparison Review

Hello everyone, I’m CH Watch Industry. I’m passionate about sharing watch knowledge, comparing authentic and replica models, disassembling and evaluating them, and helping you navigate the world of horology so you don’t get lost along the way. Longines is often seen as an entry-level brand in the watch industry, offering affordable options while maintaining strong reputation and sales. It’s a perfect choice for the working class—low-key yet elegant. The Master Series, in particular, is Longines’ most classic collection. The movement is beautifully polished, and the case is thinner than many products in the same price range. In fact, I believe Longines’ thinning technology even surpasses some high-end brands.

Today, I’m excited to introduce the Longines Master Big Mouth from GS Factory—a classic timepiece featuring a true kinetic energy display. If you’re not familiar with Longines, you might not know why it’s called the Big Mouth. The name comes from the distinct mouth-like shape at the 6 o’clock position on the dial, a playful nickname given by enthusiasts. Compared to other classic watches, it has a bit more character. The fun and charming name adds a touch of personality, giving this otherwise understated watch a unique flair.

This timepiece from the Master Collection exudes a natural elegance. With its minimalistic design and classic case, it offers a strong visual impact that makes you take a second glance. It’s like a stunning woman—so captivating that it’s hard to look away. In summer, it’s the perfect accessory to complement your outfit. Pairing it with short sleeves allows you to proudly showcase your favorite watch, making it a truly joyful and confident statement.

The Longines Master L2.666.4.78.6, affectionately known as the “Big Mouth,” is powered by the Longines Cal.L693 automatic movement. It features both a date display and a power reserve indicator. The design cleverly incorporates a “big mouth”-shaped area for the power reserve display, allowing the wearer to easily monitor the watch’s power status. Compared to traditional three-hand watches, the dial of this model offers more depth and detail. Let’s take a closer look at some detailed photos of the GS Factory Longines Master Big Mouth.

The bezel features smooth, rounded lines that highlight a refined yet masculine elegance. The lugs are small and delicate, seamlessly integrated with the case, creating a natural arc and smooth, flowing lines that are both beautiful and sophisticated. Notably, the position and size of the “big mouth” power reserve display are perfectly aligned with the original, setting this version apart from other smaller factory models.

The movement is powered by the top-tier Seagull 2836, which has been modified from the original Longines Ca1.L693 movement. All functions are flawlessly synchronized with the original, ensuring excellent performance and accuracy.

I’m sure you can all appreciate what I’m referring to here. The GS Factory Longines Master “Big Mouth” watch features a timeless, retro design with a touch of sophistication—highlighted by the small blue hands and the curved “big mouth” power reserve display. It’s simple, yet rich in detail, and carries a refined business aesthetic. A standout feature is the GS Factory’s automatic rotor, which is meticulously crafted with engravings and texture that match the original. Overall, the workmanship and the restoration of the dynamic display area are executed to a high standard.

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