Key rings come in a variety of styles, including split rings, solid rings, lobster claws, and chains. Split rings are the most common type, and are easy to use and attach keys. Solid rings are more secure, and are often used for heavy keys or keychains. Lobster claws are also secure, and have a spring-loaded clasp that makes them easy to open and close. Chains are a stylish option, and can be used to create custom keychains.