This is what I use;

 

https://www.amazon.com/Rothco-Lightweight-MOLLE-Bottle-Carrier/dp/B013CRHMDU/ref=sr_1_5?dchild=1&key...

 

I have two of them.  

I use one on my hydration pack, attached with 3/4" velcro strips (two strips).  The bottle I use with it is a 20oz stainless steel bottle.

I use the second one as a handle for my 25oz Stanley Master Thremos (which doesn't have its own handle).