A nice size medium density sponge. Use round surface to apply your base coat and the edge can hold another 2 or 3 colours to add other colours to your base. This saves you having to rinse your sponge between colours. You can add any of the existing colours back onto the sponge if you necessary, but if it's too dry use a spray mist bottle to dampen it again .. don't dip the sponge in water.