This sterling silver keyring or split ring would be a really nice gift for anyone to hang their keys on! The ring is 2.9 cm in diameter and is 2 mm thick and weighs about 5 grams. It is not so heavy that it would make your key ring too bulky and heavy!! This ring is not appropriate for thick keys like the ones for cars with the big bulky black plastic around them. It will stretch out the sterling silver ring too much. It is also not for keys that have the bulky plastic color coded covers. Sterling silver is a soft metal so if it is stretched out too much it won't spring back. Thanks!