The ACK-HMD-A01 droid was a large, six-legged droid design which was as a base model in production of different specialized droids by various manufacturers during the Cold War

The Cold War Event Cold War (3653BBY - 3642BBY)

and beyond.
Initially concieved as advanced mining droid, many droids of this design were originally produced for non-military use - for mining, construction, harvesting, salvaging and other similar purposes. But because of their durability and mobility, many droids have been repurposed by various factions for combat and defense. Like many droids of that era, this model was easily scaled, and these droids came in a wide range of sizes.