Which Dyson models does this battery fit?

It is listed as compatible with Dyson V7, V8, V10 and V11 cordless vacuums. Check your exact model before ordering, since fit varies within those lines.

Is it as good as a Dyson original battery?

It is a third-party pack, not a Dyson part. Expect it to work, but runtime and long-term life may fall short of Dyson's own battery.

How do I know if my vacuum needs a new battery?

If the vacuum runs for only a few minutes after a full charge, or cuts out under load, the pack is usually the cause. A replacement is the fix when the motor and brush still work.

Does it come with a charger or tools?

The listing describes a replacement battery only. Plan to reuse your existing Dyson charger and attachments.

Is it worth it over buying a new vacuum?

If your Dyson still cleans well and only the battery has faded, a replacement pack is the cheaper way to keep it running. If the motor or brush bar is also failing, a new vacuum makes more sense.