The most widely used marker by magicians and ballooners, the mini sharpie with small tip is indelible on most surfaces.
Also fade and water resistant, the ink dries quickly.
In addition, its formula is non-toxic.
You can take it from anywhere and thanks to the clip on the cap you can easily attach it to a key ring, bag, cord... all you need to do is pull it and here is the marker ready to use.
Use it when a card needs to be signed, for example, then leave the card as a keepsake, the highly resistant ink will allow the viewer to remember you for years.
Practical in size.
Indeleble.
Cool design.