Optically Worked Double Concave Glass Lens, 75mm Diameter, 200mm Focal Length Face Size_38mm open at one end for

open at one end for mercury barometer construction and atmospheric pressure demonstrations

Classroom kit for determining relative humidity and dew point using paired dry-bulb and wet-bulb thermometers on a sling handle

Basic 15-slide set pairs common plant and animal tissue preparations for short-unit microscopy coursework in middle school and early high school

9-inch inner diameter with a 5

and packaged as a single optics kit

Optically Worked Double Concave Glass Lens, 75mm Diameter, 200mm Focal Length Face Size_38mm open at one end forPairs 75mm of aperture with a 200mm diverging focal length on a double concave glass lens, the gentler curvature softening divergence for clearer virtual image observation in refraction setups.