When purchasing glass or metal dildos, there are a few important things to keep in mind to ensure that you're buying a safe and high-quality product:

1. Buy from a reputable retailer: Look for a reputable retailer specializing in adult toys or sexual health products. Many online retailers and brick-and-mortar stores carry a variety of glass and metal dildos, but it's crucial to buy from a reputable source to ensure that you're getting a safe and high-quality product.
2. Check for body-safe materials: Ensure the glass or metal dildo is made from body-safe materials, such as medical-grade stainless steel or borosilicate glass. Avoid purchasing toys made from cheap, low-quality materials that could harm your health.
3. Read reviews: Read reviews from other customers who have purchased the same product. This can give you a better idea of the product's quality and performance.
4. Look for a warranty or return policy: Some manufacturers or retailers may offer a warranty or return policy on their glass or metal dildos. This can give you peace of mind if the product does not meet your expectations.
5. Practice proper care: Proper care is crucial for maintaining the safety and longevity of your glass or metal dildo. Always clean the toy before and after each use, store it in a safe and dry place, and check for any signs of damage or cracks before using it.

Remember that choosing the suitable sex toy is a personal and subjective decision. What works for one person may not work for another, so take the time to explore and experiment with different types of glass and metal dildos to find what feels best for you.