The Diffraction Apparatus, order code DAK, $620 includes slits and lasers. The slit dimensions and laser wavelengths are critical dimensions for comparing experimental results with theory.
The tolerance of slit widths and separations is 3-4 microns.
The laser wavelengths are
green 532 +/- 1 nm
red 635 +/- 5 nm
Both lasers are Class 2 laser products.