Interlopers were small ships, capable of carrying ten people—apparently including the pilot and co-pilot. Their cockpit controls were generally similar to those of Galactic Republic ship, and they were considered the direct counterparts of the Republic's Bivouac transports, but they were less heavily armored than the Bivouac, trading protection for longer range and greater maneuverability.
They only carried limited weaponry, however, and this made them vulnerable to the fighters used by the Republic and Jedi, such as seekers. They thus required a starfighter escort for safety while operating in combat zones.
It is not clear whether Interlopers had hyperdrive, or if they were deployed as sublight dropships from capital ships—or even if they were atmosphere-only flyers. Their use of ion drives for sublight propulsion suggests that they may have had at least a limited sub-orbital capability, but no direct evidence is known for sure.
During the Ruusan campaign, a group of five Interlopers brought reinforcements from the Sith Academy on Korriban to the main camp of Lord Kaan's Sith army on Ruusan. This does not tell us anything certain about their capabilities, however: they could have come directly from Korriban, deployed from a larger ship in orbit, or simply been operating from a spaceport elsewhere in Sith-controlled territory.