3/8" Dovetail Rail Mount made by Kingman for the MR Series Markers.
Will fit the MR1, E-MR1, MR2, MR2 w/ EYE. This item is standard equipment on the MR3.
This item can also be used on other markers that have a 7/8" top rail (weaver or picatinny) for adding a unique carry handle or a 3/8" top mounting surface.