Domestic Long Hair is a coat description, not a breed. It covers mixed-ancestry cats with medium to long fur, in every color and pattern from tabby and calico to smoke and solid black. Some resemble a Maine Coon or Persian without sharing any of that ancestry. Adults usually weigh 8 to 15 pounds, and the fur can make them look even bigger.
Because there is no breed standard, personality and size vary from cat to cat. Most share a coat that mats without regular brushing and sheds a fair amount. Mixed genetics tend to keep them sturdy, and many live 12 to 18 years. Adopting one is a long commitment to a good brush, a safe indoor home and a vet who knows the cat. Meeting the cat tells you more than the label does.