Nope I was just going on what my aircraft has fitted.
Which is a Allied Signal UFDR and ours only records 5
And from having a look at other AIBB reports the Metro appears to be fitted with a L3 communications unit 17m900-274. I have done a search but can't pull the spec.
Air Accidents Investigation: Fairchild SA227 AC Metro III, EC-JCU
the CVR panel looks the same as ours so presume it will be a 30min tape