Energizer CA-LPE5 Replacement Li-Ion Digital Camera Battery For Canon LP-E5
7.4V, 1080mAh, Li-Ion (website states 800mah, this is a mistake)
An Energiser branded replacement batery for canon EOS450D DSLR camera, think it's worth a punt as a spare at this price, less than unknown brands off ebay and much less than the £32 for a genuine canon replacement.
don't forget your quidco (£0.04!!!!);-)