These handheld pipes are made from polished Crystals and they also come with a metal filter for the bowl. They are one size and come in 8 different types of crystal: Black Obsidian, Clear Quartz, Green Aventurine, Green Jade, Jasper, Rose Quartz, Amethyst, and Lapis Lazuli. Amethyst and Lapis Lazuli are premium stones, and more expensive. To clean, rinse with water and wipe with isopropyl alcohol, do not scrub. Crystals are heat resistant and easy to clean. Each type of crystal has its own benefits and uses. Some crystals can fade in the sun, for quartz it is rare but can occur, Green Aventurine and Lapis Lazuli can sit in the sun for only about 30 minutes, and Amethyst is quite sensitive to sun exposure.