snap to UV grid and grid size

In the uv editor you can turn on snap and under ‘snap uv element’ there is the option ‘snap to increments of grid’. Yet I cannot find any way to specify a grid size so it seems rather pointless. In fact the grid is dependent on the viewable area so most of the time it snaps to something inbetween.

Is it possible to specify a grid size within the UV editor?

Thanks.