I have them on mine too..IF the front red fiber optic breaks.{ As mine did} I found a site that sells fiber optic.The size for that site is .060 It comes in a 6 inch lengh.cost 5.00 and 5.00 shipping..bummer but I had to get it.I super glued mine in ..works better than before ..the fiber really glos nicely..
NOTE to the question..That site was not easy to put on .The front site needed quite a bit of filing..