This is a 64mm black nylon knurled knob with a base with a zinc plated steel nut. This is the BPF 640 model from Bülte.
Thanks to their knurled head, these buttons provide a good grip and optimal comfort for assemblies requiring regular adjustments. Durable and resistant to chemicals, they have a nice finish.
These parts are offered in a matte, fine-grained black nylon surface.
They can be used in all fields of activity where assembly requires frequent handling.