Largest micro SD

What is the largest  micro SD HC card I can use in my Sansa MP3 slotRadio player?

32GB should work, however there may be a database limitation on this player as there is on others. I’ve never heard if in fact there is one, or what it may be though.

By any chance, is Sandisk on the path already for developing a 64GB?

They already did . . . about a year ago.