Annic 2Pcs Silicon Manatee Tea Infuser Tea Strainers, Gray They are made of premium soft silicon, which is durable, BPA free and eco-friendly. Won't rust , discolor or add an unpleasant taste to your tea. Easy to use. Just twist off their bottoms, fill them with your favorite loose leaf tea, put the top back on and sit it in a cup of hot water to steep. Fits most standard sizes cup, mugs, and teapots. They can withstand temperatures from -22to 450. This tea infuser perches on the rim of your tea cup so you don't have to worry about fishing it out. Cleanup is a breeze. You just need to open them back up, discard the leaves and wash in warm soapy water.