True Hooks are solid and light cannot pass through something that is solid. BUT They advertise this "red" line by saying red cannot be seen below 10 or 12 ft. when you refer to the color spectrum light has everything to do with the way colors are presented. Even the darker colors. Below that 10 ft range there isnt enough light to show the color red. Its just a Dark color. Above the 10 ft range i like red hooks on certain baits. Below that level I dont think it helps. Thats just my opinon though.