Casio has put the Modern Industrial pair on sale, and it’s the first cut the collection has taken since it launched a year ago. The digital GM-5600M-1 drops to $176 at Casio US, down from $220, and the analog-digital 2100 undercuts its own list at Amazon.
That split is the shape of this deal. Casio’s store carries the square at the sale price, while Amazon lists the GM-2100BM-1A at $214.95 against a $280 list, the lowest verified price on that reference today. Both figures were checked live this morning, and neither store has posted an end date for the cut.
Only half the collection is discounted. The black-bezel GM-5600BM-1 and the plain GM-2100M-1A stay at list, so the two references below are the whole story.
The collection sits in Casio’s G-STEEL line and arrived last November, Japan first, with the US and Europe following. A full year at list is the normal run for a metal G-Shock line, which is why a first cut across half the range is worth flagging at all.
Metal over resin, on purpose
Modern Industrial takes the two best-known G-Shock shapes, the square 5600 and the octagonal 2100, and rebuilds the outside in stainless steel. The bezel keeps the forged form of the first G-Shock, with a finely uneven texture pressed across the top surface. Every exterior surface is honed matte, and the sides get a hairline finish instead, so the case catches light two different ways.
Openings cut into the lug ends expose the reinforced resin center case underneath the steel. That layering is the shock-resistant structure doing its work in the open, not trim. You can see the construction from across a desk, which is the entire idea behind the collection.
On the BM variants, black ion plating covers every bezel part except the top surface. The plating is then partially removed from that top surface, exposing the bare steel.
Casio credits the treatment with stronger abrasion resistance, and it leaves a two-tone case that still looks like one piece of metal.
Dials stay mostly black, with a single red accent on the function label. Casio ties that red to the line’s total-toughness brief, and it is the only color anywhere on either watch. Negative LCDs run throughout the collection, a plain digital window on the squares and a dial-plus-LCD layout on the 2100s. The urethane band carries a square-dot molding that echoes the bezel texture, and the key resin parts in the band are bio-based resin.
GM-5600M-1: the original square, in steel
Price: $176
Regular Price: $220
You Save: $44 (20% off)
Where to buy: Casio US
Start with the shape that started the line. The 5600 keeps the original square case and a digital-only layout, wrapped here in the textured steel bezel. Big digits, negative display, stopwatch one button away.
Specs run 49.6 × 43.2 × 13.2mm and 73g on the wrist, with a battery rated at about five years. That weight is low for a steel-bezel watch because the case center underneath stays resin, so the metal adds presence without turning the watch into an anchor. The function set is the classic one: 1/100-second stopwatch, countdown timer, multi-function alarm, and a full auto-calendar that runs to 2099. Shock resistance and 200m water resistance carry over unchanged.
Pick this one if your wrist runs smaller or you just want the purist’s version of the watch.
It wears flatter than the 2100, the all-digital read is faster at a glance, and at $176 it’s the cheaper way into the collection by a wide margin.
GM-2100BM-1A: the octagon, cheaper at Amazon
Price: $214.95
Regular Price: $280
You Save: $65.05 (23% off)
Where to buy: Amazon
Hands change the read completely. The 2100 pairs an analog dial with a digital window at four o’clock and a day subdial at nine, all inside the octagonal steel bezel.
On this BM reference the case under the bezel is black, so the exposed steel top does the talking.
It measures 49.3 × 44.4 × 11.8mm and 71g, a touch thinner than the square despite the extra hardware. Battery life is rated at about three years.
World time, five daily alarms, a 1/100-second stopwatch and a countdown timer are on board, and a double LED lights the dial and the digital window together. Shock resistance and the 200m water rating match the square, so the choice between the two is about the read, not the toughness.
Buy this one at Amazon. The $214.95 listing undercuts the $280 list by $65, and the watch sits at 4.5 stars across its first seven ratings there. If the octagon is the one you want, this listing is the route.
The two side by side
| Reference | Case (L x W x H) | Weight | Battery | Price |
|---|---|---|---|---|
| GM-5600M-1 | 49.6 x 43.2 x 13.2mm | 73g | About 5 years | $176 at Casio US |
| GM-2100BM-1A | 49.3 x 44.4 x 11.8mm | 71g | About 3 years | $214.95 at Amazon |
Under the metal, the toughness kit is shared: shock-resistant construction and 200m water resistance on both. Lighting differs, a Super Illuminator LED on the square and the double LED setup on the octagon. US specialty retail still holds both references at full list price, so the Casio and Amazon routes are the only discounted doors on these two. Prices were verified today, and Casio posts no end date, so the figures stand until a store changes them.
Between the two, the square at $176 is the cleaner buy. It’s the original silhouette, it carries the longer battery, and the discount lands on a lower list price to begin with. The 2100 makes sense only if you want hands on the dial, and Amazon’s price closes most of the gap anyway.
Either way, this is the first time either watch has moved off list since the November 2025 debut. A first discount on a four-watch collection, with two references left at full price, usually means the cut is a test. It won’t necessarily be repeated.
