The other week I spent about 5 minutes comparing bin bags to get the best deal. Was annoying as sone quoted their size as height x width, some height x diameter, some included litre-age some didnt.
Eventually settled for paying 32p more than my normal brand, but due to a special offer I got twice the number of bags capable of holding the same amount of crud bag for bag.
Can you understand now why its taken me nearly 1.5 years to decide on a washing machine.
Anyway, I use double sided sticky tape. Apply tape to poster, top edge peel n stick in place. Do sides. This is he easiest for doing it tank in situ with limited access to the back.