Free Kate Moss Nail Salon Pro Nail Polish in Mars (red) when you buy 3 other qualifying Rimmel London products.
Also combines with the current 3 for 2 promotion on Rimmel - so essentially it's 4 items for the price of 2 (cheapest item free, as always). Cheapest items are £2.99, so you could get this deal for as little as £5.98.
Nail polish added to basket automatically when you add 3 qualifying products.
Online and in store :)