This review is primarily to inform anyone looking to try this with the Tarvis 30 oz. tumbler that the fit is not exact. For about $1 more than what I was going to pay for materials to make a DIY handle for my Tarvis, I decided to try this handle out instead. It turns out that the top ring is just short of fitting once the lower ring is snug against the cup. This results in a little bit of play between the top ring and the cup, but hardly enough to be problematic and I'm still able to use the handle just fine in this state. The only caveat is that if I apply a little pressure on the handle as I put the cup back down on my desk, the lower ring sometimes loosens and "disconnects" from the cup. I decided to wrap a rubber band around the top section to take up the gap with the top ring. This worked like a like a charm, and the top ring now fits snug and also covers the rubber band, and the handle no longer loosens from the cup. The attached pic is with the "mod" in place. If a little rigging doesn't bother you, then this handle can work for the Tarvis 30 oz tumbler. For me it was well worth the $6.95.

I will still give the product a 5 Star rating on build and design alone.

Great, works as described. I was even able to use this for other tumblers I purchased at local stores. Makes it much more comfortable to use when drinking contents.

The only problem is this makes it harder to fit into cup holders in the car but you can easily remove it if you need to put it into the car cup holder. Takes a long 2 seconds of your life but I am sure you can do that while the car is warming up.

The handle fits my Reduce 34oz Cool-it tumbler perfectly. For the price it's hard to go wrong here. My only complaint - and the reason for not giving it a 5 star - is that the ribbed design of the outer part of the handle itself. If holding the cup for any length of time with any amount of liquid in it, the handle kind of bites into your hand (mine, at least). It's just flat uncomfortable - why this wasn't made a smooth area is beyond me.

I bought a Yeti-like tumbler from Marshal's for six dollars. I love that thing, but I wound up needing a metal straw for it, since it didn't come with one, and I saw this as a recommended purchase along with it. I'm so glad I bought this! It makes holding the cup so much easier! Now I can drink my 30 ounces of home-brewed iced coffee, and begin my day caffeinated and less annoyed, plus it's easier to hold :)

I actually returned this handle because I found one that was less expensive, however, I'm sorry I did. You get what you pay for and the less expensive handle was exactly less expensive because it was not as well made. The Aoocan handle was sturdy, had a good amount of finger room and conformed to my cup well which is more than I can say for the less expensive handle. The only thing I would have like different was the grooves in the handle, I would have preferred a solid handle, this is a personal preference, not a detraction from the use-ability of this handle.