This replacement Corun AAA550*2 Ni-MH battery is 2.4V 800mAh NiMH (Nickel Metal Hydride). The Corun AAA550*2 Ni-MH battery was fitted in a variety of cordless phones including Tesco cordless phones. Also printed on your old battery will be a 4-figure number, eg 0842. This is a manufacturing date code. 0842 would mean that particular Corun Ni-MH battery