Are
these the ones you mean?
If so, then I would steer well clear. They are just junk, frankly. There are no current ratings, we aren't told if the 30C is continuous, burst or just a fairy tale. I wouldn't trust them at all.
Also, a lipo is not always a lipo (bear with me) in the same way that a Mikomi TV is not the same as a Sony or a Panasonic inside. They all come from different manufacturers and are therefore all made in slightly different ways with different quality materials and workmanship.
Seriously, don't buy these
because they are cheap. As the old saying goes 'if it looks too good to be true, then it usually is'. Invest in better quality Lipos - especially for 1/8 Brushless, where the current draw and stress on batteries is high. Devote a bit more money towards the batteries, even if it means waiting a few months.