The standard one heats above ambient (typical microbiological cultures at 30-37 °C); the refrigerated one also cools below ambient (incubations at 20-25 °C, BOD, enzymes); the CO2 one adds a controlled atmosphere (typically 5 % CO2) and humidity for mammalian cell culture.

If you use bicarbonate-buffered media (the vast majority), yes: CO2 maintains the physiological pH of the medium. Without a controlled atmosphere, the pH drifts and the culture becomes stressed or dies.

Prefer smooth interiors without corners, automatic disinfection or hot-air sterilization, and discipline in cleaning and in handling the water in the humidity tray. Integrated sterilization at 180 °C eliminates laborious manual decontamination.

Models with data logging, alarms, IQ/OQ protocols and DIN 12880 compliance; for electronic traceability, integration with software compliant with 21 CFR Part 11. Binder, represented by Inolab, provides this documentary support.