This is the allowance you can take into the cabin with you, i.e. your personal hand luggage
That depends, as Aer Lingus use Stobart to operate some of their regional flights. The cabin baggage allowance for flights operated by Stobart is less generous than that on Aer Lingus aircraft.
Please view your booking to check which airline is operating your flight. All you need is your Booking Reference, which is on the e-mail confirmation that we sent you.
Below is a link to the Cabin Baggage page on the Aer Lingus website