Which mattress should I buy?

[Mum24Monkeys]

I have just bought the step2 hot wheels bed of a friend and want a new mattress.
I have been looking at websites all day and am very confused. My DS is 3 and is very bouncy so need a good mattress. The size is weird as I need a mattress 134 x 71 cm I can't seem to find a good mattress to fit.

Anyone know where i could get one?

I've had a few mattresses from Baby Mattresses Online for my 3 DGC and must say that each one has been fantastic. They do loads of different sizes on their website and even made one to measure for an old fashioned style of cot. I sent them a template and their customer service rang me to discuss the options for fillings and the covers they do. I would recommend this company.