The dropper bulb is made in Taiwan using SILASTIC RBL-9200-50 Liquid Silicone Rubber, known for its excellent chemical stability. It resists dissolving in essential oils, helping preserve the purity and longevity of your valuable oils. This high-quality silicone can withstand extreme temperatures — up to 392°F (200°C) and down to -40°F (-40°C). Even after 72 hours of hot-cold cycling, it remains clear, flexible, and crack-free. No yellowing, no hardening, and no degradation — making it ideal for essential oil applications.