1. Airtight seal: Essential oil dropper bottles have an airtight seal which prevents the oil from being affected by air and humidity. This helps to maintain the quality of the oil and prolong its shelf life.

2. Amber or cobalt glass: The glass used for these bottles is either amber or cobalt, which helps to protect the oil from UV light. Exposure to UV light can break down the chemical compounds in the oil, reducing its effectiveness and aroma.

3. Dropper top: The dropper top allows for precise dispensing of the oil, ensuring that you can use the desired amount without wasting any. This also helps to prevent spills and leaks, making these bottles ideal for travel.

4. Easy to clean: The bottles are easy to clean and can be reused, making them environmentally friendly and cost-effective. This is important for those who use essential oils frequently and need to transfer oils from one container to another.

5. Different sizes: Essential oil dropper bottles come in various sizes, making them suitable for different needs. For example, smaller bottles are ideal for travel, while larger bottles are perfect for those who use essential oils on a daily basis.

In conclusion, essential oil dropper bottles are great for storing and dispensing essential oils due to their airtight seal, amber or cobalt glass, dropper top, and ease of cleaning. They come in different sizes to suit different needs and are a must-have for any essential oil enthusiast.