Any NiMH battery that will physically fit the space and is the same 7.2 voltage. It will have a larger capacity ( mah) that will just give you a longer duration. If you're unsure ring or email component shop and tell them the size of the old battery, they will help you. Google component-shop.co.uk. they will need to know the type of connector / plug fitted to your old battery, so maybe be prepared with a photo of the old one. You can trust them to be fair and helpful.
Chas
I nearly forgot to say, please be careful disposing of the old battery, cadmium is nasty and shouldn't be put in the normal bins. Take it to a recycling centre.
Edited By Charles Oates on 13/11/2019 23:07:13