Was I too harsh on Size D threads? Size D Threads are an integral part of rod building. Here are 3 popular uses 1: Building rods for beginners. Size D Thread dramatically cuts down the guide wrapping learning curve because it’s larger and easier to wrap with. 2: Wrapping larger diameter blanks, offshore rods and large guides. 3: When you need to build a rod as quick as possible, to get on the water the next day and catch a hot bite. For the most part, Size A and D threads are interchangeable and