I bought this as a replacement for my ailing 2700mAh original dyson battery that was in my V8 since I bought it 2 years ago. As far as functionality goes, it does exactly what it should be doing. I'll get 20-30min session of vacuuming the house out of one charge compared to the 10 min session I would get on the failing battery. I had high expectations going from 2700mAh to 3500mAh but I wouldn't say it lasts that much longer but I wanted something that would last as long as my original battery used to last for and I got exactly that. Aesthetically it feels a bit cheaper than the original dyson battery and the charge indicator feels a lot cheaper made with cheap plastic but that should be the least of your worries. All in all, it works as intended and the filters that come with it are a nice bonus. I've used it for a few weeks now and have not encountered any problems so far. Time will tell if it keeps the same charge consistently but I'll post an update if it degrades rapidly.