What for an IR-Cut-OFF Filter is?

What for infrared cut-off filter is used in M12-type lenses: examples with and without, 🆚 comparison. How to remove IR-cut-off filter from a lens. What happens then.
Timing:
0:32 - daylight test with IR cut
0:42 - how to delete IR-cut filter
1:15 - daylight test without IR cut-off filter
1:58 - night test
2:46 - artificial illumination test
This M12 / 4.35 mm lens you can buy on Aliexpress: ali.onl/1qk3
#Video&Photo #WhatIsItFor? #CuriosItch #compare2