SmartLash eyelash serum is designed to make lashes and brows appear thicker and fuller without the aid of mascara, liners, or Groucho Marx masks. Each tube of the clinically-tested serum is water based, prostaglandin-free, and safe for sensitive eyes. The enhancer glides on easily with a fine-tipped applicator. Clinical studies suggest that optimal results are seen in 60 days when used as directed, but some users have reported results in as little as 28 days.