100m roll of Neon orange paracord. 3mm diameter.
Paracord or parachute cord is a lightweight nylon kernmantle rope and has been used as a utility cord by military and civilians alike. Constructed from a multiple strand core and a relatively smooth exterior sheath. It can be stripped down to its original components, the inner being used as fishing line in survival situations and the outer as a lightweight binding cord. Nylon does not rot or weaken from mildew.
1000s of uses from hide building to replacement boot laces.