A combat harness is a set of equipment for carrying military gear. It consists of a belt, suspenders, and accessory pouches. Other names for this include suspenders and load-carrying equipment (LCE) or load-bearing equipment (LBE).
This type of combat harness is widely available to characters from any Faction for about 50 KS or the local equivalent thereof. One place you can find these is at Bravemart. They are made by various manufacturers including Ketsurui Zaibatsu.
Combat harnesses like this date back to the modern era, which in the SARPiverse timeline is considered ancient history. Soldiers have a wide variety of equipment to carry and these are still useful for attaching that gear to the body in a way that is tolerable.
The combat harness includes suspenders, a web belt, ammunition pouches with grenade holders, a plastic water Canteen with cover, an entrenching tool (folding shovel) with cover, and a pouch for a small first aid kit that contains (at least) a bandage. A flashlight can be put on the opposite suspender but must be purchased/provided separately. It is usually colored olive drab or sometimes another suitable camouflage color.