Benecos Natural Nail Polish Happy Nails in the colour Rock It! is a medium grey with a hint of mauve giving a warm tone and is perfect for long and short nails. Benecos nail polishes are free from formaldehyde, colophony, parabens, silicone, phthalates, toulene, camphor and haloorganic compounds. Biotin, known as vitamin H and avocado oil helps to strengthen and nourish nails.