Hi there, I have an older cot that I was planning to use, but finding it difficult to find a mattress that sits exactly. The cot is a gumleaf nursey cot, and recommends a mattress size of 680mm wide x 1300mm long AND 150mm thick, and notes that to prevent galls the maximum mattress thickness should not exceed 150mm. I have tried to find a cot mattress to fit, but can only find 660 x 1300 (with 125 thickness), OR 680 x 1310 (with 125 thickness). How do I know if this is safe to use? The sellers have said they are SIDS compliant and the sales rep said it will be fine - but I just want to make sure and buy a new set if not. thanks