Each map in the Discovery series covers an area 40km x 30km and is produced at a scale of 1:50000 (2cm to 1km). This is about  one and a quarter inches to the mile. They are the most detailed commonly available commercial maps. Practically all the townlands are indicated but not their boundaries. As a guide the maps retail in Ireland at Euro 7.10.

They can be ordered online at:

Ireland:
http://www.irishmaps.ie/

U.S.A.
http://www.globecorner.com/welcome.html

Canada
http://www.interlinkbookshop.com/iremap.htm

New Zealand

http://beehivebooks.co.nz/index.htm