G-Shock Mudmaster GG-B100XMH-5A Gives the Rugged Tool Watch a Gold-Toned Glow-Up

By Elliot Nash - News

Updated: 6 August, 2026

ShareCopy Link0

Readtime: 3 min

Every product is carefully selected by our editors and experts. If you buy from a link, we may earn a commission. Learn more. For more information on how we test products, click here.

The G-Shock Mudmaster usually looks like something you’d pull from a rescue kit, construction vehicle or military supply crate. It’s enormous, aggressively labelled and covered in enough exposed hardware to make it a properly chunky boy on the wrist.

But with the new Master of G Land Mudmaster GG-B100XMH-5A, Casio has given the watch a literal glow-up, dressing it in dark brown resin and a light yellow-gold ion-plated stainless-steel bezel. The handsome colourway appears across three watches in the Master in Horizon Gold collection, inspired by the golden line where the earth meets the sky.

Even on an absolute unit like this, it somehow works. The muted gold looks closer to aged brass or expedition hardware than jewellery, while the black dial, gold-toned numerals and bright red seconds hand keep everything relatively easy to read, even amongst the chunk. It’s a proper makeover for the Mudmaster, but that doesn’t make it any less ridiculous.

1/6

Design & Dimensions: Master of G Land Mudmaster GG-B100XMH-5A

Brown and gold can certainly add a touch of class to a watch designed for professionals working in the toughest environments. But Casio has done absolutely nothing to hide the heft.

The GG-B100XMH-5A measures 55.4 × 51.3 × 19.4mm, making it nearly two centimetres thick, with oversized buttons, labelled guards and exposed screws surrounding the dial. At 104g, the weight certainly matches those oversized proportions.

Brown ion-plated hardware ties the bezel into the dark brown bio-based resin case and strap, while the gold-toned hour markers and hands stop the black dial disappearing beneath its protective structure.

The Full Outdoor Toolkit Is Still Here

Casio says the collection is meant to evoke “the awe-inspiring power of nature”, but the makeover hasn’t taken away any of the tools the Mudmaster is known for.

Its carbon-fibre-reinforced resin case uses Casio’s Carbon Core Guard structure, with shock resistance, mud resistance and 200 metres of water resistance. A mud filter helps stop dirt entering the case, while the glass-fibre-reinforced resin caseback adds another layer of protection.

The watch also packs a digital compass, altimeter, barometer, thermometer and step counter. Bluetooth connects it to the Casio Watches app for automatic time adjustment, location functions and Mission Log, which combines altitude data from the watch with route information recorded by your phone.

Power comes from a CR2025 battery rated for approximately two years, rather than Casio’s Tough Solar system.

The Mudmaster joins the Mudman GW-9500MH-5 and Gravitymaster GR-B300H-5A in the wider Master in Horizon Gold collection. It’s priced at ¥60,500 (roughly AUD$544) in Japan, while Australian pricing and availability remain unconfirmed.

Casio has cleaned up the Mudmaster’s colour palette, but everything underneath remains gloriously excessive.