Hi,
I think there’s 3 types - Only available with Red top-sheet, marketed as BH rubber.
H3 National 37 degree
H3 Provincial 37 degree
H3 (standard) 37 degree
Basically there’s now a 37 degree hardness sponge for 3 of the 4 versions of H3, H3 National Blue sponge is only manufactured with a black top sheet I believe.
I don’t think a 37 degree version has been readily available outside of China until this year, it’s only starting to filter through to Europe now. I think it was available in Japan / Hong Kong etc first.
I haven’t seen any 37 degree versions available from TT11 and they seen to stock all the versions of H3 that were available, I’m sure they will have them soon.