"A buoyant, multi-purpose rope manufactured from polyethylene fibers. With a smooth, hard and nonabrasive surface it has excellent weather resistance properties. Ideal for outdoor use, this rope has a high resistance to abrasion and wear. The design, as well as the splice structure, makes it easy to melt the ends.
UV resistance class 4/5*. (breaking strength is cut by half in about four years in high radiation.) " -piipposhop.com

Tough universal rope, needs to be strored sunprotected.
Price is for one meter, if you order a pleised loop or plan to make one the rope is of course gettin shorter. Dependeing on the size of the loop. 
The thinner ropes fit to make Tuglines or necklines, the thicker ones for attaching sledes.
But ropes can be used for whatever you like to.
 
Small amounts might fit into a letter. If you are unshure ask, and i will test it. Letter is allowed to be 3cm thick.