Prusament PETG is an in-house-made filament at Prusa Research. The whole manufacturing process is closely monitored and tested - guarantee ±0.02mm precision and highly consistent colors.  You can inspect the parameters of every spool made at prusament.com. 

Prusament PETG Carbon Fibre is an in-house-made filament at Prusa Research, reinforced with carbon fibre, improving some of its mechanical properties whilst still maintaining an attractive look.  Compared to regular PETG the material has better dimensional stability, temperature resistance, higher modulus of elasticity and is less prone to stringing.