It is a feature/bug. There are brands that do different cup sizing per country. See the case of Parfait By Affinitas (http://www.bratabase.com/browse/parfait-by-affinitas/size-range/) where they have many versions, so if you search for 28G you might end up seeing 28I, 28G or 28DDDD for the case of Chantelle (http://www.bratabase.com/browse/chantelle/size-range/). This complicated scheme can make searches quite complex in order to match what you might mean, is a 34J (US) a match for a 34GG (UK) in Curvy Kate (http://www.bratabase.com/browse/curvy-kate/size-range/)? And we never got into FR vs EU sizes. To save these inconsistencies and also make not the site choke every time a search is made, I had to be pretty loose on these filters so you will see unexpected sizes there, some are close and some might seem totally off but it is because the brands have not made up their minds on what they mean by cup sizing.
Same thing for 28F - it shows also 28FF.
It is a feature/bug. There are brands that do different cup sizing per country. See the case of Parfait By Affinitas (http://www.bratabase.com/browse/parfait-by-affinitas/size-range/) where they have many versions, so if you search for 28G you might end up seeing 28I, 28G or 28DDDD for the case of Chantelle (http://www.bratabase.com/browse/chantelle/size-range/).
This complicated scheme can make searches quite complex in order to match what you might mean, is a 34J (US) a match for a 34GG (UK) in Curvy Kate (http://www.bratabase.com/browse/curvy-kate/size-range/)? And we never got into FR vs EU sizes.
To save these inconsistencies and also make not the site choke every time a search is made, I had to be pretty loose on these filters so you will see unexpected sizes there, some are close and some might seem totally off but it is because the brands have not made up their minds on what they mean by cup sizing.