Funny, when you Google "délimiteur magasin", you get several references to "séparateur" and none to "délimiteur".

http://www.google.com/search?rlz=1C1SQJL_enUS779US779&ei=hCS...

I think this is Google telling us that they're synonyms. Wordreference.com also gives it as a synonym:

délimiteur nm (séparateur) delimiter n

I couldn't find any references to "delimiter" in a retail context, and I think "separator" works better. They're almost certainly shelf separators for loaves of bread, but even if they're not, this should be understandable. Shopffitings can be tricky to translate because every company gives them different names.

Here are some pictures of "séparateurs":
http://www.magequip.com/equipement-magasin/separateur-tablet...