Usually two, sometimes three.
One is a Parker T-ball with a gell cartridge.
One is a dual point (fine & Medium) sharpie.
In my PSK is a space pen. Most of the time I have all three.

The T-ball is a stainless steel pen. I have several. The one I EDC is the one with the newest refill. Very robust pen. Writes on most surfaces.

I also carry a small piece of tyvec (how is it spelled??) which is a near indestructible paper. The sharpie on this is very weather resistant. Thanks to a thread here about using tyvec. Works great.

If I am doing a project, (archeology, ham radio etc.) I usually carry a mechanical pencil. Been using them for years and no failures.


Nomad