Open hoops are ideal for people who find small fastenings or fiddly closures difficult to use. Simply pull open and then once it's in your nose, you just push it back together to secure. The CZ crystal on this hoop is 3mm and the hoop itself measures 9mm high x 9mm wide x 2mm deep and has a gauge measurement of 24ga. Weighing just 0.1g, it's super lightweight which makes it very comfortable to wear.