This Remington manufactured second variation alloy open (rear) sight leaf is for the early pre-grade model 552 Speedmaster semi-auto rimfire rifle which uses the shorter height dovetail mounted front sight. This piece is in very good condition retaining most of its original factory finish with some light wear.  (file photo)

Note: Firearms with the following serial numbers have been observed with this part: N.S.N. OH (July 1961), (October 1965) & RO (November 1977 Ser. # A1431560) 

1464240 & 1713644