Whats your thoughts?

Has anyone tried these Tenergy 4/3AF and are they a safe or good alternitive to Li-ion’s.

http://www.ebay.com/itm/30-x-Tenergy-4-3AF-18650-Size-3800mAh-NiMH-Battery-Flat-Top-No-Tabs-/390405386727?pt=US_Rechargeable_Batteries&hash=item5ae5f971e7

they are 1/3 the voltage of 18650s so im sure they will not work in almost all lights, with the exception of a very select few

I thought so, voltage plays a big part as does mah. I am new to this part of electronics and thanks for your input!