haven't been able to find one for the H version yet. It's easy enough to get an element for the C but I think the heat version is a non standard size supplied direct to Baxter. Every time I meet with the rep from Fileder I ask him when they will be coming up with an alternative but I don't think they are actively looking at it.
Heat sanitisable membranes are available from all the usual manufacturers but they all seem to be only 40 inch 4040 or 8040 types.
I suspect the ones for individual ROs are specials for the RO manufacturers.
The Purite ones are OK and are relatively very cheap but too long for non Purite machines - about 20"