This special pattern for a shirt with a round divider is a must-have! Finding the right divider was quite the adventure. The recommended divider is a big D-shaped ring but this was unavailable in the requested size at a haberdashery. Subsequently, I acquired a self-locking shackle from a ships chandler where I was asked about the type of vessel I own! A first attempt showed the shakle was too heavy. Further research online led me to a swimwear accessories shop where I finally found a round divider. Bingo!