best battery for the fw3a?

It was designed to accept only a standard flat-top cell from any manufacturer (flat tops are almost always very very close to the 65mm standard). I run the Sony (now Murata) VTC6 and they do great. Samsung 30Q is another great choice, as is the similar Molicel 18650. Generally these 3000mAh cells can deliver a bit higher current, which will allow turbo to shine a bit brighter. If you want to use a higher capacity cell in the 3500mAh zone that’s ok, you’ll just lose a little brightness on turbo (and actually, in the end, overall run time may be a washout between the two unless you typically use the light only at lower brightness levels). I don’t know what the current crop of 18650 cells from Vapcell is like - they’ve had some great ones and they’ve had some defects and duds, too. The Lishen cells are also generally pretty good. Is it NKON there in Europe that is a preferred supplier? On Aliexpress you could buy from the Vapcell store (they often have OEM cells in addition to their rewraps), the Sofirn store, or the Convoy store. I can’t recall if Wurkkos has a flat top available but I think they’re using the same Lishen cells that Sofirn does, just with their branded wrapper. The prices and shipping costs on Ali are not very good for US customers, not sure if it’s better for you or not. Also, if you have any vape stores in your area you can often get good cells from them, too.

samsung 30q flat tops is a good choice dont need more amps then that really. most flat tops unprotected should fit no matter brand.

Thanks all! I’ve bought the Samsung 30Q from nkon.nl, it fits perfectly! My mistake was that I am using 30Q in my Sofirns, they have a small button-top, and I forgot that they come with flat-top, too.