The question for Cluster size on SolidState Disks and Memory Cards, pendrives, etc... is not just as simple as use the less size allowed.
A lot of SSD, Pendrives and memory cards has a physical block size when writting to them, so the best choice is to figure out what that value is (no way to consult it thill what i know).
The efect is the next:
-If Operating System writes a block of 512Bytes and the pendrive really writes blocks of 4096 bytes, it will make that 8 blocks of 512 bytes each that are written by the operating system will overwrite the same 4096 bytes 8 times because each time the pendrive hardware will overwrite 4096 bytes on each write operation
That is just because the SolidState memories do writes by blocks, but such block size is not the same than the one used by the Operating system when formatting a parttition, etc..
The best is to make the OS to use the same block size for formatting than the real physical block size that will use the hardware.