In or out? Taking the views on Dublin's Grafton Street
According to the UK government, trade with the Republic of Ireland is worth £28bn a year.
Ireland is the largest export market for food and drink from Britain, and the two-way trade between the countries is worth an estimated £1bn every week.
A significant slice of that makes its way through Wales - with Anglesey's Holyhead port the second busiest passenger port in the UK.
In Dublin, shoppers on the city's famous Grafton Street show just why the republic is also Britain's second largest export market for clothing and fashion.
But what do they make of the EU Referendum? BBC Wales' George Herd went to find out.