Cogsets come in two verities, cassettes or freewheels, of which cassettes are a newer development than freewheels.
Cogsets come in two verities. Cogsets come in cassettes. Cogsets come in freewheels. Cassettes are a newer development than freewheels of two verities. Cassettes are a newer development than freewheels of cassettes. Cassettes are a newer development than freewheels of freewheels.