It is a Galilean-Type lamp. The Slit width and length are continuously variable from: 0 to 14mm and 1 to 14mm respectively.

Specifications:
Total Magnification Ratio: 6x, 10x, 16x, 25x, 40x
Eyepieces: 12.5x
Diopter Adjustment: ±6.0D
Slit Angle: 0°~180°
Slit Inclination: 4° step: 5°, 10°, 15°, 20°
Filter: thermal safety, UV, red-free, cobalt blue
Aperture Diameters: 14, 10, 5, 3, 2, 1, 0.2
Fixation: Green LED

Model: HR-20.350