The housing is black UL94 V-0 rated thermoplastic.
The key selection decision against a lower-count sibling like the 86837-410HLF (40 positions) is purely the circuit count on your BOM — the pitch, current rating, and overall contact length are identical across the series. The 0.600" (15.24mm) overall contact length with a 0.380" (9.65mm) mating section and 0.120" (3.05mm) solder post gives a consistent stack height and board standoff regardless of position count.
Because there's no shroud, the mating half needs to provide its own polarization or keying if mis-mate protection is required in the assembly.