If you haven't read the manuals. We all get busy.

The EPS and EPS Carry use the 1620 battery.

The 407k and 507k use the 1632 battery. Same size foot print as the 1620 just a little taller.

As a result the 1632 will not work in the EPS or EPS Carry it won't fit. But the 1620 will work in all four optics.

I have a buddy who's optic 507k was dead (he forgot to order some) and I was out of 1632s. I gave him a 1620 and it worked and he qualed that day (his bug) said he had no issues with the optic.

The more you know.

This is good info I was kind of ticked off when I found my EPS had the odd ball battery and I had to stock another battery.

Glad it helped. I thought it was worth passing on.

Very good info.  Thanks for posting it!

Good to know

That reminds me of the old Photon brand keychain lights from over 20 years ago. IIRC, Some of them took a 1632 while others took two 1616s to push the LED with higher voltage (blue, maybe another color also).


C: Denotes that the battery chemistry is lithium.

R: This means that the battery has a round shape.

16: The two numbers immediately following the letters CR mean that the battery has a diameter of 16 millimetres.

32: The last two numbers denote the thickness, which in this case is 3.2 millimetres.


18650s and other cylindrical batteries can be figured the same way.  Many years ago, I had to figure out what size dummy battery I needed to replace a rechargeable battery with standard CR123s.  I can't remember what size battery I was replacing, just it was an old and cheap nicad Surefire-like light.

NYE 1999, the smokeshow bartender Id been crushing on for years wasnt tending bar, she was out for the night.  I had one of those keychains, they had just came out.  She was looking for a lighter.  Held out the led to light her butt, she tried, I laughed, she laughed, we got married.  Been with her ever since.  she doesnt tend bar or smoke anymore.  shes still a smokeshow.

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