Answer: Double Thick Cover!
This is also sometimes referred to as simply “DT.” Paper mills that focus on making high-end fine papers only can create paper up to a certain weight (e.g., 100 lb. Cover). But you and I like the feeling of a nice, very substantial – and thus very heavy – sheet. This is where DTC comes in.
Two lighter weight Cover papers are laminated together to form one heavy Cover sheet. A 130 lb. Cover DT, for example, is made from two 65 lb. Cover sheets laminated together, to look and behave as one.