The battery's part # is D51.
Don't get the D51R, the positive and negative posts are reversed, you want the D51.
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My previous battery was a regular style lead acid battery, a Sears DieHard. Right after I installed my 3 amp stereo system with one JL 12W6, I would get alot of headlight dimming even when the DieHard was still fresh. Eventually after a year I killed it and got the Optima. It's cut down on the dimming alot, but not 100% - maybe 90%. But you can completely drain an Optima over and over and over again, get a jumpstart and let the alternator juice it back up, and it'll be fine. You can't do that more than a few times with a normal battery.