HobbyKing is great but the buyer has to do a bit more homework/research themselves.....
There is a LOT of battery options - some at very cheap prices but have to check the dimensions
Yes they do some airsoft batteries - though the airsoft batteries they sell are limited in burst rating = C
and some of them are 166mm long which is too long for crane stocks - aprox 125-ish for crane stocks
diameters also vary - G&G cranes are a bit narrow 18mm max tubes - others have a diameter in tube of 22mm
MP5k's - jeeeeeeez they are like 17.999999mmm diamter and a number of single stick batteries are f*cking tight
If the buyer measures their battery compartment - and I STRONGLY advise checking by making up a dummy battery
from cardboard, sticky back plastic washing up bottle or something ffs to triple check....
Then they "may" find they can get a small compact block type battery which is a bit cheaper and more mah than HobbyKing's Airsoft ones
Also buyer beware you can easily order 1 battery from UK and another battery/charger from HongKong
If UK are out of stock - next place is to get them from EU (Netherlands)
in fact last time I checked HobbyKing Airsoft batteries come from HongKong or EU - not sold on HobbyKing UK
Yes an Imax B6 (genuine) is a good mofo charger but will need psu unless you buy the B6 AC version
plus if on mini tamiya you may need to get some adapter leads to charge the mini tamiya lipo on a B6
hence for ease of use the B3 type is a lot easier to use out of box no matter what connector your gun uses on lipo's
So for an ease of life - component shop
if buying in bulk loads and upgrading - HobbyKing but do ya homework properly first