Pros: When it works, it makes the laptop works much longer with two batteries.

Cons: Junk. Ordered on July 3, and today, July 30, died already.

Pros: Owning a ThinkPad W520, it adds 3-4 hours of battery life. It also serves as a wedge and elevates the laptop, allowing better cooling from beneath.

Cons: Purchased in August of 2013, it died today on Jan 28, 2014 -- so it lasted roughly after 5 months of use. My ThinkPad tells me the battery cannot be read, there is a battery error and thus will not charge. Though it lasted longer than the 4 weeks other posts mentioned, I expected better from a "business" grade battery, especially for the ThinkPad line. To not even last a year is inexcusable, not to mention barely a month for the others? So with my battery problem along with the other issues detailed in other posts, it is evident there is something wrong with this particular model battery slice.

Since there is a 1 year manufacturer warranty from Lenovo with this battery, I am crossing my fingers that there will be no issue getting it exchanged out for a new one. Also the Lenovo site does not have a place to submit a warranty request for the battery, so I ended up submitting the request as if it were a laptop. Otherwise I would just call their technical support line.

Pros: Awesome added battery life, does add a tilt to the laptop which I appreciated

Cons: Makes for one heavy laptop when this battery is installed. Also, it died after about 4 weeks of use. I expected at least a year or more. No option but to replace either and at this price, I'm wondering how long the next one would last?

Other Thoughts: Would not recommend buying one unless they last longer than this one. I'd expect a year at least!

Pros: Well, I can fly to Europe and back with my t430 on a single charge, so, y'know, there's that.

Cons: It's pretty heavy, so if you can't lift an 8 lb laptop for some reason, this thing probably isn't for you. Of course, I've always been of the opinion that it never mattered how thin a laptop is. See 'pros' section for why i don't give two hoots about the heft.

Also, be forewarned that, for reasons beyond all reckoning, Lenovo disabled force discharging of batteries in their (nonetheless awesome) newer battery control firmware, so you can't really do wear leveling between two batteries anymore. This battery will thus wear a tad more quickly than the internal battery, so I just charge it to about 80% and store it when I don't need to go 28 hours without a charge.

Other Thoughts: Man; ain't technology just grand?

Pros: doubled Life while it worked

Cons: Died after 3 weeks of use
added some serious heft