This Winchester manufactured third variation 30-B series rear sight leaf with the "V" shaped sighting notch, 5/8" side wings, and patent dates is for the circa 1912 or earlier manufactured model 1906 slide action rimfire rifle. The condition is very good exhibiting a brownish gray patina with light wear. (file photo)

Note: Winchester model 1906 takedown slide action rifles with the following serial numbers have been observed with this part:

100K: 148297, 162122 & 167513

300K: 312061 & 333347

400K: 442486