VESSEL was a member of the committee who established the JIS (Japan Industrial Standards) after World War II because they were (and "are") the leading company of various tools in Japan.
The JIS has been treated as a kind of reference or guidance for the screws (and screwdrivers), and what is important to the screw manufacturers is not the cross recess on the screw head, with which the tip-end of the screwdriver has contact, but the thread design of the screw in the end.
VESSEL has been monitoring the commercially available screws and checking the matching with them, and if necessary, modified the specifications. This has made their bits to be suitable for a wide variety of screw, not only JIS but also other standards.
Screwdriver Hex Bits - Vessel TD-BS2
Screwdriver Torx Bits - Vessel TD-BS3
Countersunk Screw - Brass (Nickel Plating)
Countersunk Screw - Steel (Trivalent Chromate Black)
Countersunk Screw - Polycarbonate (Transparent)
Countersunk Screw - Self Tapping - Steel (Nickel Plating)
Flat Washer - Steel (Trivalent Chromate)
Hex Nut - Flange Nut - Serrated Steel (Trivalent Chromate)...