The bottle is convenient to use for cold brewing, and easy to carry around. I believe it's designed for hot water brewing, but I can't think of any of my tea that can be hot brewed in this way. I use it for a few Taiwan oolong that I didn't like in normal brewing but later found nice in cold brewing. A couple of green teas work well in this way too.
The major drawbacks are: 1) it's still plastic (but so far I don't like carrying glass bottle or non-transparent bottle); 2) Its tea cage is quite small. I wish it were at least twice as large.
3 days ago