Micro slotted set screws
These are  products of Saita Seisakusho Co., Ltd., the world's top manufacturer of precision set screws.
Since the company cuts screws by chasing with a cutting tool, the accuracy of coaxiality of the flat tip with respect to the screw shaft is within 0.01mm.

A cutting die is used to process the threads in a general cam-type automatic lathe.
When the pitch 0.25 of M1 is processed with a cutting die, the tops of the threads are likely to be chipped. At our company, we process threads by chasing with a cutting tool in the same way as with NC lathes, so chipping at the top of the threads rarely occurs.
Free-cutting steel rusts easily, so the standard products are galvanized (trivalent) in black and white. Other plating (electrical nickel plating, electroless nickel plating, etc.) is also available as a special order item.
Stainless steel (equivalent to SUS303) is partly available as a standard product.
The total length and other materials (brass, aluminum, phosphor bronze, nickel silver, etc.) not shown in the table are made to order.