Graphite refills are good for all surfaces, are water soluble and give good contrast.
Red, yellow & white refills are designed for all surfaces, are water soluble, have good contrast however are not temperature resistant.
They are designed to write on many different surfaces, from dry to wet or oily, and smooth or glossy surfaces.
Replacement refills are available in various colours for different applications.
Blue, green and white refills are water resistant and designed for all surfaces. They are ideal for wet cutting of tiles and stone.
Pica Markers are a good choice for multiple applications. The standard pencil comes with a cap containing a sharpener, and one lead.
Photo is indicative only, all leads are graphite.