Sturdy white ceramic teapots have a special "Tea Control" brew basket. The "Tea Control" brew basket features a twist lid that you turn to stop the brewing. In the "brew" position, the infuser is open like any other infuser. When you turn the control, an internal mechanism pushes the leaves tightly against one side of the basket to force out the water and stop the brewing. This prevents the tea from over-steeping and becoming too strong and bitter.