Phillips Drives Detail

The Phillips screw drive (specified as an ANSI Type I Cross Recess[10]) was created by John P. Thompson, who after failing to interest manufacturers, sold his design to businessman Henry F. Phillips.[11][12] Phillips is credited with forming a company (Phillips Screw Company), improving the design, and promoting the adoption of his product.[11] The original patent[13] expired in 1966, but the Phillips Screw Company continued to develop improved designs.[11]
Phillips drive bits are often designated by the letters “PH”,[11] plus a size code 0000, 000, 00, 0, 1, 2, 3, or 4 (in order of increasing size); the numerical bit size codes do not necessarily correspond to nominal screw size numbers.