Pluriel pour Kit-Kat ?

Question

Pourquoi est-ce qu'il ny a pas un "s" au fin de "Kit-Kat" dans la phrase "Alors, deux McFlurry Kit-Kat...."?

Accepted Answer

Jim, I think this is the same as it is ‘supposed to be’ in English (at least according to Apple) !   
https://www.dlaeditors.com/blog/product-names-plural#
Trade names are registered and have a specified form.
The advice to not use a plural form is often broken in English, but perhaps more observed in French as it is similar to the convention with surnames, and doesn’t usually change pronunciation ? 
An example from a search result ‘toutes les Renault Captur..’
            Voir toutes les RENAULT CAPTUR d'occasion en vente chez les concessionnaires Renault, partout en France. Un large choix de RENAULT CAPTUR : automatique, ...