I have used one of these personally for years now.  Aside from making a great cup of portable tea, they are also a great conversation starter.  People are amazed by them.  You can see the loose leaf tea expand and dance around in your cup.  These are very popular with students and people who love tea and are on-the-go frequently.

Easy to use, easy to clean

Durable, lightweight design

Perfect for brewing loose leaf teas

Yields 1 1/2 cups or 12.85 fl. oz.

3 piece set includes mug, twist off strainer and lid