Every square G-Shock goes back to one watch. Casio engineer Kikuo Ibe wanted a watch that wouldn't break when you dropped it, and in 1981 a three-person group called Project Team Tough set out to build one. Their target was the Triple 10 concept, which meant surviving a 10 metre drop, resisting water to 10 bar and running for 10 years on one battery. After about 200 prototypes, the answer came from watching a child bounce a ball in a park. Ibe suspended the module inside the case on a few points of contact, so it floated instead of taking the full hit.
The result was the DW-5000C, launched in April 1983 in black and red and in black and gold. It had a stainless steel case inside the resin, a screwed-down steel case back and 200 metre water resistance. Sales in Japan started slowly. Casio's American hockey-puck advert for the DW-5200 helped turn it around. The shape has been made ever since, and the watches below are its direct descendants.
DW-5600C, the last basic screw-back
The DW-5600C arrived in 1987 and stayed until the mid 1990s. It kept the original's stainless inner case and screw-lock back, and it was the last basic 5000 or 5600 square built that way. That's why collectors chase it. Keanu Reeves wore a DW-5600C-1V through the 1994 film Speed, and by most accounts it was his own watch. NASA flight-qualified the DW-5600C and the later DW-5600E for space travel.
The 5600C was made with two modules. Module 691 ran from 1987 into the early 1990s, and module 901 came later. Watches were built at two factory locations, marked Japan A and Japan H. All of them work the same way, but collectors rate module 691 and Japan A watches as the rarer ones. These are now forty-year-old resin watches, so original bezels and bands are a wear item. Casio ran a limited restoration service in Japan in 2018 and 2019 that swapped the bezel, band and battery. Aftermarket bezels exist too, so a crisp bezel on a 1980s square is often a replacement.
DW-5600E, the everyday square
The DW-5600E is the one most people picture. It drops the screw-lock back but gains an EL backlight, which G-Central rates as an upgrade on the 5600C's light. It ran for years on module 1545. Around 2010 Casio moved it to module 3229, which stretched the auto calendar out to 2099. The 3229 manual quotes accuracy of plus or minus 15 seconds a month and about two years from a CR2016 cell, with frequent use of the light shortening that. In 2017 Guinness officials drove a truck weighing just under 25 tonnes over a DW5600E-1, and it survived.
In late 2023 Casio started replacing it with the DW-5600UE. That version uses module 3525, an LED light and a longer battery life. Casio America and some big retailers sell the new watch under the old DW5600E-1V name. A listing that says DW-5600E can be either one, and the module number on the case back tells you which.
GW-M5610, the set-and-forget square
The GW-M5610 came out in 2009 as a solar version of the 5600, with styling that nods back to the DW-5000C. It took over from the GW-M5600 of the year before. Tough Solar charges it from daylight or room light, and Multi-Band 6 sets the time from six radio time signal transmitters around the world. Reception takes two to seven minutes and usually works better at night, away from buildings and electronics.
Until 2021 it ran on module 3159 with an EL light. In July 2021 Casio replaced it with the GW-M5610U on module 3495. The U version gets an LED light with selectable afterglow, a choice of date format, five world time slots across 48 cities and a home and world time swap. The outside looks almost the same. The GW-M5610U-1B and some other versions have an inverted display with light digits on a dark background, which looks sharp but reads harder.
GW-5000, the steel screw-back square
The GW-5000-1JF launched in 2009 as a Japan-only tribute to the 1983 original. It brings back the stainless steel screw-lock case, adds a DLC-coated case back, and keeps Tough Solar and Multi-Band 6. It's made in Japan. In July 2021 the GW-5000U-1 replaced it on the same module 3495 as the newer GW-M5610U, with the LED light. The U version also reached Europe as the GW-5000U-1ER. G-Central lists it at 74 grams against 51.7 grams for the resin-cased GW-M5610, so it feels noticeably heavier on the wrist.
How to tell them apart in a listing
From the front these watches look almost the same, so lean on the details sellers can photograph.
- The case back. A round, threaded screw-lock back means a DW-5000C, a DW-5600C or a GW-5000. The DW-5600E and the GW-M5610 don't have one.
- The module number. Casio stamps the module on the case back. For the 5600C look for 691 or 901. The DW-5600E shows 1545 or 3229, and 3525 means you're looking at the newer DW-5600UE. The solar squares show 3159 before 2021 and 3495 after.
- The light. The older modules use an EL backlight and the U models use an LED. If the case back isn't shown, ask the seller which light it has, or for the module number.
- The suffix. JF marks a Japan-market watch and ER a European one. A GW-5000-1JF or GW-5000U-1JF is the Japanese release that many buyers import.
- The weight. If a listing claims a GW-5000 but the seller can't show a screw-lock back, ask them to weigh it. The steel case is about 20 grams heavier than a resin GW-M5610.
What to check on any used square
Resin is the part that ages. Casio's own manual warns that sweat and water left on a resin band or bezel cause premature wear, cuts and breaks. Look closely in the photos at the band where it meets the case and at the keepers, and zoom in on the bezel corners. An EL backlight also loses brightness after very long use, so ask the seller for a photo or short video of the light on.
On a battery square, a dead display usually just needs a new cell. On a solar square, a blank screen may be the power-saving function. Leaving it in bright light should bring it back, and a seller can check that for you. Ask for a photo of all four buttons doing something, and make sure the display shows every segment.
The square shape lives on in other models in the catalog too. The DW-6900 followed the 1994 DW-6600, the first G-Shock with an EL backlight. The 2019 GA-2100 took design cues from the DW-5000C for an analog-digital case. If you're choosing your first watch, our guide to your first Seiko or Casio covers where the squares fit.
Which square to buy
Buy the DW-5600E if you want the shape and the toughness and don't mind changing a battery now and then. Pick the GW-M5610 if you never want to set it or open it again. The GW-5000 is for people who want the 1983 construction, steel and a screw-lock back, with modern solar and radio inside. The DW-5600C is the collector's square, and with that one the module, the factory and the originality of the resin all matter.
