Tamiya Weathering Master C (Orange rust, Gun metal, Silver)

Orange Rust (for orange/red tinted rusty metal

Gun Metal (for unpolished metal look)

Silver (for polished metal look)

Easy Way to a Pro-Level Finish
Weathering
means adding realistic-looking effects to your models, such as sand on
tank treads and mud-caked rally car bodies. These new Tamiya Craft Tools
offer by far the easiest way to achieve realistic weathering effects.
Weathering Master comes in a pocket sized case with 3 colors and special
applicator tool. The pen-type Weathering Stick offers up to 5mm of
easy-to-apply color by simply twisting the tip.