This is a BSA Optics Rifle Scope known as the Sweet 17, model S17-312X40.
The Windage and Elevation turrets have zero reset with "Allen" screw. Each model in the Sweet 17(TM) series have a side adjustable parallax setting of 10 to infinity. (With the exception of the model S17-27x32 which is 7.5 to infinity)
Features:
Turret calibrated for .17hmr
Adjustable parallax
