I have just this week received the sights which I ordered from Brownell's for the .450 #2 which I'm building. The fibre-optic front sight is made by a company called Hi-Viz. It's made of steel, comes in 4 different heights, fits a standard 3/8" dovetail, and comes complete with 6 different F/O inserts. 3 are in chartreuse in sizes 1/16", 3/32", and 1/8". 3 are in the same sizes in fire red. It takes about 30 seconds to switch inserts with the help of the little plastic gizzie supplied for the job.The 1/8" fire red, combined with the hell-for-stout NECG, 2 leaf express rear, which I just filed up last evening, suits my 63 year old eyes like a pair of new eyeglasses. I can't say enough good about this sight, and I'm not easily satisfied with equipment. They certainly are a lot more succeptible to breakage than metal sights and they need to be protected with a hood which is made for them with windows in it to admit enough light to catch the F/O.