Long range stealth orbital drop pod
From Halopedia, the Halo wiki
Long Range Stealth Orbital Insertion Pods are a more advanced variant of the UNSC Human Entry Vehicle used by the ODSTs for "helljumps". Unlike HEVs, which must be launched from a vessel in orbit of the target, Long Range Stealth Orbital Insertion Pods can be launched while a ship is actually in slipspace. To date they are the smallest manned UNSC ships that are capable of transitioning into normal space safely. Still, they are, according to occupants, a "bumpy ride."
Their construction consists of simple Titanium-A covered with Lead Foil and a Stealth Ablative Coating to make the ships radar invisible.