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 a 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.