I received it today and installed it right away on a 2012 Prius, perfect fit!. If the old battery is dead, you have to use the new battery to connect it to the car with a jumper cable at the fuse block, then juice will flow into the door and windows and also the hatchback so you can open it. I imagine a battery charger will do the same trick. Anyway, happy as a bird now, the Prius is back in business.

Perfect fit right down to the overflow tube. My old battery voltage was 5.9 volts with a 200 amp load. The old battery would never have survived another New York winter. This was well worth the $129 and the hour it took to install. This is a small price to pay for piece of mind that my car will start on those cold mornings. I would bet this battery will outlast the car. Don't believe those sites that tell you that you need the $229 version, at least not for the 10 Prius. This was far better than the OEM battery I removed.

This battery fit my 2004 Prius perfectly and installation was easy (I printed a copy of instructions I located online).
This included a tip to connect 12V to the car BEFORE disconnecting old battery (or you will lose all your radio and other settings).
To do this, there is a connection TAB for the POSITIVE inside of the fuse box (under hood in front of driver).
Be careful connecting the positive, because (if careless) you could damage something.
You can connect the negative clip to any bolt on the chassis.

This fit my 2008 Prius perfectly and works like a charm. I bought one of these batteries six months ago and the negative post broke off while installing the battery, which happens sometimes. Amazon sent me another one the next day, free of charge, and didn't even have me go through the bother of sending the broken one back. This one installed without a hitch and has been great. Always get something like this through Amazon as they work hard and very fast to honor warranties and attend to claims.

This battery arrived double boxed, with the inner box having closely fitted Styrofoam pads around the battery. It was in perfect condition and had a 95% charge when it arrived (Florida to California). It is an exact size and fit to the OEM 12-volt battery for the 2nd generation Prius (2004 - 2009, see pictures). There is an excellent video on you tube on how to replace the generation 2 Prius 12-volt battery called, "Gen 2 Prius - replacing 12v battery". Follow the video sequence, but here are some helpful hints:

1. Connect another 12-volt battery via jumper cables so you will not loose any of your settings (radio, maintenance schedule, etc.) The location of the positive jumper post is under the fuse box cover located on the driver's side within the engine compartment. There is a red plastic cap that swings up. The negative is connected to the upper shock tower bolt. The other car battery supplying the 12-volt voltage you see in the first and third picture is from a Mercedes.
2. The only tools you need are a 10mm socket (tall one), socket wrench and extension.
3. If you loosen the positive cable, you can move the connector so that the 10mm socket and extension can fit between the brake power supply module and the battery hold down bold (chassis floor bolt).
4. The vent tube twists at the battery to remove and reassemble.
5. When reassembling, the battery ground wire (negative) goes under the Optima strap. The strap should be pushed down on it's slots so the Optima strap is somewhat flush with the top of the battery.
6. In order to hold the 10mm screws/bolts in the socket when reassembling so they do not fall down under the battery, use a small piece of paper towel (just enough to cover the 10mm head) so that the 10mm screws/bolts are a tight fit within the 10mm socket when starting the thread within the screws/bolts holes. You can blow it off or use any kind of wire or screw driver to remove the piece of paper towel to continue to tighten the 10mm screws/bolts.

The entire 2nd generation Prius 12-volt battery replacement took 1/2 hour, including the taking of the pictures.