You are in total control of exactly how long you want your tea infused by a flick of your wrist. Fill the borosilicate double-walled flask with hot water, fill the stainless steel mesh filter with your favorite tea and drop the infuser into the flask. When you want to stop the infusion process, simply flip the flask upside down - the mesh filter will attach itself to the cap so that when you flip the flask back up, the filter will be out of the water.
"I didn't know this but the infuser actually comes out along with the cap so you don't get your hands dirty. The only thing I didn't like is that the filter drips tea but it's not anything that can be controlled. So I bump the filter on the side of the glass a few times before I take it out."