TLDR: Great Tumbler. Short enough to fit under the Portafilter Head of my Rocket Classic, and holds a good double shot + a touch of water/milk. Loses one star for not having a spill proof top.
I had been looking for a travel cup that would fit under the portafilter head of my espresso machine for some time before I found this. Every time that I had to pull a shot into a shot glass and then pour it into my old travel cup that didn't fit under the portafilter it would make me sad to see all that wasted crema.
With this tumbler I can pull the shot directly into the cup, and avoid all of that wasted deliciousness, and the volume, 6.5 ounces, is a perfect size for people that like really strong Americano's, or macchiato.
My only complaints with this tumbler (one is not really an issue for me but could be for other people) is:
1) The lid is not spill proof. There is one hole for venting and one hole for drinking, and no plug/sliding device to seal it shut, so you have to be careful not to knock this bad boy over, or jostle it about too roughly.
2) The lid has a pretty significant lip to it that seats into the cup, which limits the usable volume in the cup. This isn't an issue for me as I only put ~4-5 ounces of fluid in it (Double Shot + splash of hot water), but if you were looking to live on the hairy edge of that 6.5 ounces you will most likely be spilling out of the top.