Product Overview The PHEFON FS-12L Vaccine Cooler Box is a passive insulation cold box engineered for the safe and reliable transport of vaccines. Designed to meet the rigorous demands of the medical and pharmaceutical industries, it maintains vaccine efficacy and potency during transit — even in challenging environments. With a CDC-approved design, the FS-12L ensures vaccines remain within the critical 0–10°C temperature range, supported by a cold life of up to 24 hours.