The following options are available: MODEL Spectrum VR3 Standard VR3 Upgrades C1 to C2 OC Air/Nitrox to OC & CC Air/Nitrox + 58 C1 to C3 OC Air/Nitrox to OC Trimix + 114.00 C1 to C4 OC Air/Nitrox to OC & CC Air/Nitrox Trimix + 173.90 C2 to C4 OC + CC Air/Nitrox to OC + CC Air/Nitrox/Trimix + 116.33 C2 to C3 OC & CC Air/Nitrox to OC Trimix + 56.40 C3 to C4 OC Air/Nitrox/Trimix to OC & CC Air/Nitrox/Trimix + 55.23