This is one 0,5 kg spool of 1,75 mm RED FilaFlex.
Filaflex is the original elastic filament for 3d printers.
This new revolutionary material is a TPE (thermoplastic elastomer) with a polyurethane base and some additives to make it printable in your 3d printer.
Filaflex has an incredible elasticity that allows you to create elastic printed parts for your projects.
Read specs and recommendations here