This is typical for unshrouded BERGSTIK headers; the mating half must provide the positive lock if vibration is present.
Compared to the 10-position 87901-410HLF at the same 0.100" pitch, the 87901-440HLF carries 40 positions — matching the circuit count for a wider bus or a denser I/O bank. The pinout is straightforward: two rows of 20 pins each, all positions loaded. The overall contact length is 1.040" (26.42 mm), with a 0.820" (20.83 mm) mating length and a 0.120" (3.05 mm) post length for the through-hole solder joint.