A range finder includes an improved module structure, that facilitates injecting a transparent filler uniformly into the entire light guide spaces neither leaving any unfilled region nor impairing the characteristics thereof. AFFS comprises a rotor-powered craft, fitted internally with a jet engine collinear to the length of the fuselage which has an air intake projecting through the rear of the fuselage. The base forms a through slot and the two fixer members are pivotally connected to the base on opposite sides of the through slot.