How big is the icon on a USB flash drive to make it clearer? (Inside)

I made my own by tiling,

Generally an icon file will contain 3 sizes at the same time:

When viewed as tiled it's 48 x 48,

When viewed as icons it's 32 x 32,

When viewed as a list it's 16 x 16,

I've tried them separately 128*128 64*64 48*48 32*32 16*16

Obviously the first icon is the clearest (used 48*48)

The second one is 128*128, not the bigger the size the clearer it will be, lots of jaggedness. Depends on the situation.