Casio Duro MDV-106 MDV106-1A

The Casio MDV-106-1A, marketed under the Duro line and nicknamed the "Duro Marlin" for the fish engraved on its caseback, is a 200-meter quartz dive watch introduced in 2011. It pairs a stainless steel case and unidirectional bezel with a Casio quartz module built on a Miyota base, and became widely known after being repeatedly photographed on Bill Gates's wrist.

The Casio Duro MDV-106 was introduced in 2011 as a 200-meter dive-styled quartz watch built around a stainless steel case and a marlin fish engraved on the caseback, which led collectors to nickname it the "Duro Marlin." According to Teddy Baldassarre, the model was a mainstream commercial success, reportedly selling over 600,000 units in its first decade, and it launched at approximately $50.

The watch's public profile rose substantially after Bill Gates was photographed and filmed wearing an MDV106-1A on multiple occasions. Two Broke Watch Snobs documented one such sighting during a July 2020 appearance by Gates on "The Late Show with Stephen Colbert," where he discussed philanthropy, wealth, and taxation while wearing the watch. Writer Michael Penate, quoted on the site, called it "fun to see a wealthy guy...rock a sub-$100 dive watch that has grown in popularity among our readership," framing the choice as consistent with what the article described as Gates's practical, understated style.

The MDV-106 is powered by a quartz movement that Casio labels Module 2784 on the caseback, per Casio Fan Mag's archive listing, which also records a rated accuracy and a three-year SR621SW battery. BladeReviews' review notes the same ±20 seconds per month accuracy rating, though it reports that real-world testing on its unit showed gains of only one to two seconds per week — better than the rated tolerance.

BladeReviews also states that despite the "2784" module designation printed on the case, a commenter provided evidence that the movement underneath is actually a Miyota 2115 (a Citizen Group movement), with 2784 functioning as Casio's own module reference number rather than a distinct in-house caliber name. The watch retains a screw-down, guarded crown to help protect the movement and support its 200-meter water resistance rating.

Multiple reviewers note that the MDV-106 wears smaller than its dial suggests. The Brooks Review observed that it "wears smaller than the face looks" and reads as more upscale from a distance than its price implies, attributing this to short, curved lugs that pull the case in close to the wrist; the same review found the dial "overly flat" and lacking the dimensionality of pricier divers, limiting it, in the reviewer's view, to straightforward timekeeping rather than dial appreciation.

12&60's review describes an initial lack of enthusiasm that changed with wear, concluding the watch "grows on you as you progress through your experience" and stating the reviewer would "wholeheartedly trust this watch underwater." Millenary Watches similarly reports that the watch "punches well above its weight" and remains "extremely practical" even paired with more formal clothing, aided by its short lug-to-lug and curved lug design.

Lume performance draws more consistent criticism. BladeReviews found the luminous fill "begins fading almost immediately and will be all but invisible within a few minutes," though it remained usable in full darkness outdoors, while the Brooks Review called the lume "decent enough" but said it could be stronger.

Teddy Baldassarre's review states the Duro launched at roughly $50 in 2011 and that current retail across the model family runs from about $70 to $90 depending on colorway, strap material, or bracelet configuration. The Brooks Review, revisiting the watch in December 2022, put its own unit's original 2018 purchase price at about $40, noting the same reference had risen to "just under $50" by the time of the re-review — reflecting gradual price increases over time rather than a single fixed MSRP. 12&60 separately cited a going rate of "$60 / £65" for the reference at the time of that review.

Several reviewers flag the stock resin strap as a weak point: the Brooks Review calls it "comfortable and durable" but "visually ugly," and recommends budget aftermarket straps, noting the watch's 22mm lug width (an uncommon size relative to the more standard 20mm) still has ample aftermarket strap support.