Flip-up aiming sight

An aiming system mounted on a handgun having a front, rear, top, bottom, and two lateral sides, said handgun having a frame, a slide and a fire control mechanism actuated by a trigger, said slide displaceable on said frame and forming the handgun top, said slide housing a barrel in a slide forward end, said barrel cooperatively linked with the slide and, together with the slide, defining a longitudinal firing axis, said aiming system incorporated onto the slide and comprising:

• a front sight vertically protruding from said slide near the handgun front;
• and
• a rear sight mounted on the handgun slide near the handgun rear, said rear sight comprising:
• a base unit having a front, a rear, a left side, a right side, a top surface and a bottom surface, said base unit front and rear defining a base unit longitudinal axis, said base unit longitudinal axis being parallel to the handgun longitudinal firing axis;
• a flip-up lens pivotally attached to said base unit, comprising:
• an aiming lens having a perimeter portion of one color and a central portion of another color, said central portion having a geometry selected from the group consisting of:
• circle, polygon, oval, and cone;
• and
• a lens frame holding said aiming lens, said lens frame having distal end, a proximal end, a left side, a right side, a front surface and a rear surface, said lens frame distal and proximal ends defining a lens frame longitudinal axis, said lens frame longitudinal distance along its longitudinal axis being less than the base unit longitudinal distance along its longitudinal axis.