Available in six shades — including one that's transparent and one for grey hair — the new Revlon ColorStay Brow Fiber Filler (£9) is all about adding volume and definition to your arches. The tinted gel formula is not only waterproof, but it's also silky and flexible, so it won't flake halfway through the day. And thanks to tiny little fibres in the gel, it helps add length and volume to your natural brow hairs.