Style 4 (BS) is a vertical mount printed circuit board connector with exit leads on a .100 x .100 grid. It has the same number of footprint rows as the mating face ie; 9 thru 37 has 2 rows, the 51 has 3 rows and the 100 has 4 rows. Jackposts for coupling are optional. For new applications, we suggest you consider Style 6 which has a denser footprint of .075. Style 4 configuration is in accordance with slash sheets 22 thru 27 of MIL-DTL-83513. ("M" series only).