Specifications Fieldmicroscope Mini Magnification (x) 20x (fixed) Optical system Upright, unreversed image; eyepiece diopter adjustable for right eye; 51-to-52mm interpupillary distance adjustment Field of vision (mm) 11 (diameter) Angle of view (º) 12.8 Vertical adjustment 42mm from the base of stage Eye relief (mm) 12.8 Plate Removal and reversible (top: flat; underside: built-in cup) Dimensions (mm) (In use) 156-202 (H)x89 (D)x90 (W) (Folded close) 124(H) Weight (g) Approx. 395 Accessories S
Easy blowing, High tone dog whistle, fitted with solid, waterproof pearl, to give a trill for those who want a distinctive and different sound. With a frequency that fluctuates by 750 Hertz. 210 Small ultra high pitch whistle has a natural cork ball which produces the familiar 'trilling' roll of the pea whistle. 210.5 Same as the 210 but with out the cork ball, produces a single extremely high frequency.