Casio G-Shock GA100-1A1 Review Military Watch

Casio G-Shock GA100-1A1 Review Military Watch

My rating: 9/10. Excellent watch. Value for money.

Today I’m doing a Casio G-Shock GA100-1A1 review. Casio’s range of G-Shock watches focuses on creating extremely durable timepieces that are shock and vibration resistance with a great level of water resistance included. I’ve always been a fan of these G-Shock military style watches and love their oversized chunky design. They’re built with a thick resin that protects the stainless steel casing, this gives the G-Shock watches that added protection.

You’ll see from this extensive G-Shock GA100-1A1 review just how good these Casio watches are, and their awesome value for money.

Casio G-Shock ga100-1a1 Review

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G-Shock GA100-1A1 Technical specifications

Let’s start by taking a brief look at some of the main specifications for this G-Shock GA100-1A1 review. This just allows you to quickly grasp some of the more important details of this watch before we take a look at it in more detail.

  • Model Number: GA-100-1A1
  • Crystal Material: Mineral
  • Case Diameter: 52mm
  • Movement: Japanese Quartz
  • Extra Features: Day & date display / Stopwatch / Alarm
  • Water Resistance: 200m / 20 bar
  • Strap Material: Black rubber resin


G-Shock GA100-1A1 Design And Build Quality

The GA100-1A1 military design watch looks stunning in my opinion. It has that cool stealth black design with a military flare that makes it a big fan favourite. The GA100-1A1 has an impressive dial design with the use of analogue and digital displays. I love the use of the white detailing for the hands that draws your eyes in. The whole watch features this extra durable oversized design with a casing diameter of 52mm, that’s pretty damn big.

As for the build quality, this G-Shock watch is built to withstand most things you can throw at it. Built with the keen sportsperson in mind the watch can withstand shock and vibrations as well as being 200m water resistant.

GA100-1A1 Dial

The dial has this typical G-Shock military style to it with a multi-window display using both analogue and digital to display information. The digital displays have a colour reversed setup that displays the writing in white on black rather than black on white. Whilst this looks nice aseptically it can make it harder to read in the dark.

As I mentioned before, the use of white hands really makes the time display stand out which makes it very easy to read this part of the watch.

ga100-1a1 review banner

GA100-1A1 Sizing

As you would expect with most G-Shock watches this model has that classic oversized design to it. With its thick resin surround, it puts this watch at an impressive 52mm in case diameter. What’s great also is the thickness of the watch, G-Shock fans love that chunky military feel to it and this model has a case thickness of 17mm, more than enough to keep you happy.

GA100-1A1 Crystal

This G-Shock watches features mineral glass, exactly what I would hope to find on a watch of this style in this price range. Mineral glass is specially hardened to offer more protection from scratches and knocks. While it’s true to say the more expensive sapphire glass offers better scratch protection than this mineral glass, it doesn’t however, offer that same shock & drop protection. Mineral glass offers much better shatter resistance than sapphire glass so is a lot more suited for this type of watch.

Strap & Clasp

The strap of the watch fits in perfectly with its chunky durable design. It’s made of a durable resin that’s very comfortable to wear. It’s 25mm wide which is a bit larger than average but suits the design of the watch very nicely. It has a double tang buckle for extra security that you’ll see from the picture featured after this section.

GA100-1A1 buckle

GA100-1A1 Water Resistance 

The G-Shock GA100-1A1 features a water resistance of 200m also known as 20 bar. 200m water resistance is very good and by Wikipedia‘s example is ‘Suitable for professional marine activity, serious surface water sports and skin diving.’ So if water sports is your thing and you’re after a watch can deal with that level then this 200m water resistant watch would be perfect for you.

The thing with water resistance testing is that it’s done in a still environment with no added pressure. So 200m resistance doesn’t mean you can take it 200m deep. The very motion of moving your arm would increase the pressure forced upon a watch greatly from that that it would experience just submerged.

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The GA100-1A1 Movement

This Casio G-Shock watch features a Japanese Quartz movement. It’s fair to say that Quartz movements are fairly common, mainly due to their great accuracy and affordable cost. They work by synchronising a quartz crystal with an electronic oscillator. The electric current then causes the quartz to pulsate at a precise frequency which gives you this great accuracy for a modest price.

GA100-1A1 Pros & Cons

For all of you skim readers who aren’t up for reading a full GA100-1A1 review I’ve added this little pros and cons section for you.


  • Extremely durable resin design
  • Popular oversized design
  • Accurate Japanese Quartz movement
  • 200m water resistance suitable for professional marine activity, serious surface water sports and skin diving
  • Mineral glass offers you great protection from scratches and knocks.
  • Features a backlight for easier reading at night
  • Has a perpetual calendar system meaning you never need to adjust the date for the varying amount of days in each month



  • Due to its oversized design, this watch may not be so suitable for people with smaller wrists
  • The digital display has a reversed colour system which can make it a bit harder to read


A Final Word On The Casio G-Shock GA100-1A1

If you’re after a durable G-Shock military watch then this model would be perfect for you. It has lots of features and is built to last with its great durable design.

As with most of the G-Shock collection, this model offers great value for money in my opinion. The GA100-1A1 is one of the most popular G-Shock watches for Casio and it’s easy to see why the all black design is well sought after in the watch community. So with an all black design and genuinely well-built watch it’s a popular choice.

Overall I hope you enjoyed this G-Shock GA100-1A1 review and I really recommend the watch. Having taken into account all the aspects of the watch such as design, build quality, materials, features, and pricing I gave this watch a well deserved 9/10 from us at The Watch Blog.

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Where To Buy The G-Shock GA100-1A1

This model is available from a few places online. Personally, I always stick to recommending retailers I’ve actually purchased from. Below you’ll find a link to the sales page for this watch on each of my recommended retailers websites. I’d suggest checking out all 3 to find the best value for money available to you.


Thanks For Reading

I hope you enjoyed having a read through of this extensive G-Shock GA100-1A1 review. As always let us know in the comments what you thought of this watch.