The SMS Weathering Markers are an oil based paint marker, designed to apply rust and chipping marks with ease on your models. 

Simply draw on where you wish the effect to be and then, if needed, use white spirits to manipulate the oil paint to create realistic and natural finishes. 
Contains 4x 0.7mm tip Markers : 

Light Rust
Red Oxide
Dark Brown Rust
Brown Rust

Clean up with White Spirits / Turpentine etc.