For B2B buyers, the choice depends heavily on the application. For essential oils, prioritize Amber or Cobalt Blue glass to provide UV protection and prevent oxidation. For pharmaceuticals, ensure the glass is Type I (Borosilicate) or Type III (Soda-lime) depending on chemical sensitivity. Pay close attention to the neck finish (e.g., 18/415 or DIN 18) to ensure compatibility with droppers, sprayers, or roller balls. Additionally, verify the brimful capacity to ensure it meets your exact filling requirements.