GRP compounds???????

[stegger]

forgive me if this has been answered, couldn't find anything in a search.
I don't want the stir up again what happened at kiddy, but i saw some posts saying why the GRP tyres were not an option and this was due to it not being a control tyre. Which got me thinking about the GRP tyres i thought there were 3 compounds A=soft B=medium C=hard . Looked on the Mirage site and the only ones they do are the C (hard) is this right ?And will they bring out the 2 other compounds or have they already been out and didn't work on our tracks and that's why Mirage don't seem to have them?