This black Realflex filament is biodegradable and made from PLA. It has the strength of PETG, the flexibility of TPC and the ease of use of PLA filament. Realflex adheres very well to the print bed and has a very low shrinkage factor and virtually no warping during printing. The flexibility can be perfectly determined by varying the wall thickness and infill. Realflex has a very nice matte finish and is super strong.
Note: not every extruder is suitable for printing flexible filament.