It came upon me about 2 years this Feb. It design allows interchange of fiber colors for (hunting) backgrounds (Spring-Summer)- (Fall-Winter). The peep is rubber coated for string serving added security. I will get some more posting pics uploaded. The fibers (colors) are replaceable while peep is installed. Easy change out, and replacements. Fibers 1/16 inch ends are melted into peep with a lighter flame; into tapered peep tracking sockets.