1. A security device having a lenticular device, comprising: a first image strip pair having a first and second image strip; a second image strip pair having a third and fourth image strip; a first portion of a first image in a first colour and a first portion of a second image in a second colour located in the first image strip; a second portion of the first image in the first colour and a second portion of the second image in the second colour located in the third image strip; a first portion of the first image in the second colour and a first portion of the second image in the first colour located in the second image strip; a second portion of the first image in the second colour and a second portion of the second image in the first colour located in the fourth image strip; a first lenticular focusing element located over the first image strip pair; a second lenticular focusing element located over the second image strip pair; wherein: the first and third image strips are different from each other; the second and fourth image strips are different from each other; in a first viewing direction, the first and third image strips are viewed by the first and second lenticular focusing elements, the first image is viewed in the first colour, and the second image is viewed in the second colour; and in a second viewing direction, the second and fourth image strips are viewed by the first and second lenticular focusing elements, the first image is viewed in the second colour, and the second image is viewed in the first colour.