2016 battery will fit in a reddot that takes a 2032. It will even turn on the dot. The issue comes when you shoot your pistol. The 2016 will move inside the battery compartment and cause intermittent issues leading you to question your reddot. They look the same upon causal inspection. My key fob takes a 2016, one must have gotten mixed up with my 2032s. FYI.