There are several important factors to consider when buying sunglasses, including:

1. UV protection: The most important factor to consider when buying sunglasses is the level of UV protection they provide. Look for sunglasses that block 100% of both UVA and UVB rays to protect your eyes from harmful UV radiation.
2. Polarization: Polarized lenses can help reduce glare and improve clarity, especially when driving or participating in water sports. Consider polarized lenses if you spend a lot of time in bright sunlight.
3. Lens color: Different lens colors can be more suitable for different activities or lighting conditions. For example, gray lenses are good for bright sunlight, while brown or amber lenses are good for overcast or cloudy conditions.
4. Fit: Sunglasses should fit comfortably and securely on your face to ensure that they don’t slip or fall off during activity. Look for sunglasses with adjustable nose pads or temples for a customized fit.
5. Durability: Look for sunglasses that are made with high-quality materials and construction to ensure that they last for a long time. Scratch-resistant coatings can also help protect your lenses from damage.
6. Style: Sunglasses come in a wide variety of styles and designs, so consider your personal style and what looks good on your face shape when choosing a pair.

By considering these factors when buying sunglasses, you can find a pair that not only looks good but also provides the necessary protection and performance for your needs.