Hell3D Filament is one of the best grades filaments available. Please note that it is branded as Mambawire for the South African market.
These fibers are extremely strong and cause the filament to increase in strength and stiffness. This also means that the 3D printed parts will be much lighter and more dimensionally stable, as the fibers will help prevent shrinking of the part as it cools. However, due to the added fibers, these specialty materials are more likely to clog and can require special hardware to avoid damaging the printer. Please read here for more info.