Hi-Lux Optics 1/2in 60 Degree Type Standard Base with Slight Radius Drilled Matte Black. Malcolm 3X and 6X short telescopic sights. This base has both posa and half moon cuts. The hole spacing of the predrilled holes measures approximately 0.560" (14.2mm) from center to center. Specifications for Hi-Lux Optics 1/2in 60 Degree Type Standard Base: Manufacturer: Hi-Lux Optics Color: Black Finish: Matte Features of Hi-Lux Optics 1/2in 60 Degree Type Standard Base Standard 1/2" 60 degree base with Malcolm short sights Slightly Radiused Compatible with both round and flat barrels Package Contents: Hi-Lux Optics 1/2in 60 Degree Type Standard Base Hi-Lux Optics M050SB: 1/2in 60 Degree Type Standard Base with Slight Radius Drilled Matte Black