Cashback is for spending with your AIB or BOI Visa card at bookdepository.com
1) login to activate cashback offer at:
BOI = https://boi.visaoffers.eu/ / AIB = aib.visaoffers.eu
2) then spend with your bank card at Book Despository - sale items are here: https://www.bookdepository.com/bargain-shop/?a_aid=irishlinks
Even better bookdepository cashback deal today at Quidco https://www.quidco.com/search/?search=The%20Book%20Depository