This is definitely a necessary battery upgrade for anyone that bought any of the hard drive based sony camcorder. The battery that came with the camcorder has about 90 minutes or so of battery. However, with this battery you get about 300 minutes. This is enough for anyone. Plus, if you get the portable charger, you can charge one batter while you use one. From my experience, this is good for the whole day of filming. Normally, you do not record the whole time.

I would highly recommend getting this battery. It is definitely worth it and much cheaper on Amazon than at circuit city or best buy.

I have been using the battery for the past 6 months and there have been no problems. I haven't used my power cable since I got the portable charger and this battery.

Have just charged this battery as a back up for a trip we are about to make. The NP-FP90 series battery I previously purchased through Amazon works well.

I have two of NP-FP90 since Sep. 2006 for our trip to Grand Teton & Yellowstone NP.
While receiving them, I charged and discharged them completely for three times and they had pretty stable performance. It still have over 95% of capacity if I just left it along for three months and then still played as very beginning.

I give it five stars after owning them for more than six months. Considering of getting the third one so that they will cover more the recording time on my DCR-SR100 with SQ.

This bat. lasts for ever....it lasts 4x as long as the one that came with my Sony camcorder.

Good to have as a extra,bulky though, good to use as a battery for play back,or in case main one dies