Hey guys ... Well I'm thinking of buying a spare BL-5J battery for my N900, and the prices on eBay are simply too good to resist :P

So basically my question is, are they safe ? I know they are probably not original Nokia stuff (if I'm wrong in assuming this, please correct me so), but still can they be safely used with a N900 ? Do note that even though the model number is the same, all the buyers there currently are only listing 5800 XM as being compatible with the battery .. ?

Any info regarding the above would be greatly appreciated