I’m also on the look for one for my x220.

I’m pretty sure any original looking battery at this point is either fake or stored for so long it does not make sense to buy one.

Last time I almost bought a KingSener, but it’s really hard to find long term reviews on batteries.

It depends on the model, but usually people claiming long stretches are on low brightness, Bluetooth off, CPU undervolt and using something like TLP.