DeWALT 20V Max Brushless 1/2" Impact Wrench Kit w/ 1.7 Ah Battery & Charger Expired

At first glance, this seems like a screaming hot deal for the 921. Currently $229 for the tool only at HD (which I would never suggest paying). I am so tempted to just grab it despite being in the market for the big brother mid-torque 891....decisions, decisions.

I also believe this bare tool was part of the (now expired) HD promotion. After hack, that would have put the tool only price around $120-$140 (I cannot confirm as the deal is dead). https://www.homedepot.com/p/DEWAL.../316627128

FWIW, this thing beats Milwaukee, which was surprising to me. TTC video here:

https://youtu.be/EddtTr71fSw

That's a typo apparently. Dewalt is frankly about as simple as anyone for MUST USE, slightly more complicated for BEST PERFORMANCE. In a nutshell:
All batteries have a capacity (1.5-15ah currently available) and a maximum amperage discharge which isn't exactly documented. Bigger and more batteries can increase both, but there are tradeoffs. Below are the current lines as best I can summarize in a quick post.

12v line - AFAIK 12v is 12v for the most part, bigger batteries may perform a little better
20v line - regardless of LMNOP alphabet soup they all can use 20v or 60v batteries
Flexvolt/60v line - must use flexvolt 60 v batteries
All tools pretty much benefit to a degree from using a larger battery as more and larger cells can typically discharge at a higher amp rate. There are two specific sub model lines with added benefits:
Flexvolt advantage - performs best with flexvolt batteries (15 cells per battery) but also gains performance from larger capacity 10 cell batteries like the 5ah and up
Power detect - similar to flexvolt advatange but not optimized for flexvolt specifically.

Essentially all dewalt batteries other than this one are made from one of two cell types 18500 and 21700s, 21700s have more capacity and can discharge more amperage, adding more cells adds to the discharge ability. You can tell by the "width" of the pack which cells are used, and the height of the pack you can tell how many cells. All current flexvolt batteries I'm aware of use 15 cells (4v x 15=60 or 20 when run as 3 sets of 5 in series) where 20v can use any increment of 5 cell sets in series. Powerstack being the exception, currently available as a 1.7ah but a larger version is coming, they use "pouch" batteries that take up a lot less space and have a high discharge limit, but the current unit at least has a very low capacity.