British & Irish Roots Collection.
This is not a new set of records; it is a variety of records already available on the supplier's Local and World databases gathered into a distinct collection spanning 400 years and focussing on migration between Ireland & Britain and North America.
I had a high ol' time during December mining the collection for emigrants in my extended ancestral family, and rather assumed the free access would have ended with the New Year, but today when I checked, I found that the free access is still live.
I've no idea for how much longer this will be the case – no expiry date was ever set by FindMyPast – but it seems worth a reminder to Irish family historians to get digging while the door remains open.
The collection holds some 98 million records. The free access allows you to view all transcription and some (but not quite all) images.
For a fuller description, see my blogpost from 11 December.