You get peppermint leaves, pure and simple. And lots of them – 100g of leaves is a lot bulkier than 100g of Assam, for example.
They’re great quality, too. You just get quality leaf, no rubbish. I used to think that Teapigs peppermint (at £4.15 in the supermarket for 15 “tea temples”, I just checked) was the best quality, and whilst they are undeniably good quality and taste great, they’re also very expensive.
If you don’t mind the slight faff of brewing loose leaf then 100g of this stuff tastes pretty much exactly the same and only costs £5.90 for 100g.
I brew for a long time and go for multiple infusions. I tend to just add the infuser back in when I’m getting low and top up with hot water until the peppermint taste is very light.
Then again Teapigs also sell 100g of loose leaf for a comparable price, so who knows :)