Slit diaphragm, variable, "demo" on support

For experiments in diffraction and interference, precision slit
diaphragm mounted to pivot on support, slit width may be set
symmetrically from 0 to 5 mm
Slit length: 30 mm
Support: L=90 mm, D=10 mm
Mount diameter: 120 mm
Distance from centre of mount to support end: 150 mm