Henry F. Phillips patented his screw head design in 1936. The key advantage of this design was the ability to self center. This allowed assembly operations to hold the center during fast rotations. It allowed for faster production lines
In 1946 these same handles appeared again as a Phillips set
ST-3 Phillips #1 Shank Length 3 inch 1946 – 1958
ST-4 Phillips #2 Shank Length 4 inch 1946 – 1958
ST-6 Phillips #3 Shank Length 6 inch 1946 – 1953
ST-8 Phillips #4 Shank Length 8 inch 1946
STS-1 Phillips #1 Shank Length 1 inch 1946 – 1958
STS-2 Phillips #2 Shank Length 1 3/8 inch 1946 – 1958
ST-012 Phillips #1 and 2 Shank Length 6 inch 1946
SDWP-241 Phillips #2 3 7/16 inch long 1960 – 1965
SDWP-133 Phillips #1 7 inch long 1960 – 1965
SDWP-123 Phillips #1 7 ¼ inch long 1960 – 1965
SDWP-244 Phillips #2 9 ¼ inch long 1960 – 1965
SDWP-355 Phillips #3 12 ¼ inch long 1960 – 1965