The K2 Combo supports a wide range of filament types - including PLA, PETG, PET, ABS and carbon-fiber reinforced options like PLA-CF.
However, there are some restrictions to be aware of: flexible TPU filaments are not compatible with the CFS (Creality Filament System) due to feeding issues. Also avoid using damp BVOH/PVA filaments, or warped cardboard-type spools.