I've used Hi-Viz, Dawson, Novak, and Warren's FO tubes. Hi-Viz and Warren look red to me. Dawson looks a little pink. For green, Hi-Viz looks more yellow when compared to Novak's green FO tube. I would say the diameter of the tube would be the biggest variable when it comes to brightness. I prefer Dawson, Novak, and Warren when it comes to FO front sights since they don't use a proprietary tube design like Hi-Viz...