Please pay attention to the size comparison in the second picture showed. The size details are listed below. (1) Diameter 4mm (2) Diameter 5mm (3) Diameter 6mm (4) Diameter 7mm (5) Diameter 8mm ***Shipping, Delivery Time and Duty***A tracking number is available for all our shipping service, which means all our packages can be tracked. In our store, we can combine shipping. So the additional item(s) is FREE SHIPPING, no matter how many you buy. You can add items to the shopping cart and make one-time payment. As for the delivery time, for most of Asian countries, US, UK, EU, Canada, Australia, New Zealand, the Economy Shipping normally takes 12-22 days. And for other countries, it normally takes 12-28 days. However, for all countries, sometimes it may take more than 30 days due to the Customs, Post, Weather, Flight and Holiday. Of course, all buyers can upgrade to an express shipping, which normally takes 3-7 days for most of countries of the world. We are NOT responsible for any customs or import duties. The buyer pay any customs or import duties that may apply. ***What is Sterling Silver***Sterling Silver is an alloy of silver and other metals, usually copper. The silver contains at least 92.5% and the other metals at most 7.5%. All our items are genuine sterling silver. ***Why some items are not 925 or 990 stamped***This happens during the production process. The main reason is that the module is too small for stamping 925 or 990. If this might cause any problem for you, please contact us to confirm if the item is stamped. Thank you very much.