Generally 3–4 km long, they used Conjoiner drives for propulsion, and were also coated with a thick caul of ice that protected against minor impacts at relativistic velocities and acted as armour against the attacks of other ships. The great size of the lighthuggers enabled them to carry vast numbers of passengers and huge amounts of cargo.
Lighthuggers also possessed a limited repair and redesign capability. They were capable of moving rooms or machinery around within their hulls, or stripping material from one point to repair another. At least some were also equipped with "manufactories", which could build a considerable range of devices, given the relevant specifications.
Their small, point-defense weapons -- ostensibly defensive in nature -- were capable of blasting a 200 kilometre crater in a planet and disrupting weather formations in a fashion similar to a large geological event, such as an asteroid impact or volcanic eruption.
Most lighthuggers were owned or ruled by their crew of Ultranauts, who, because of their long stretches in reefersleep and constant hopping from one star system to another, were mostly divorced from baseline humanity. They were characterized by extreme modifications, often in the form of replacement or mechanical limbs or even holes right through them.
By the time of the Human-Inhibitor War, there existed a fleet of lighthuggers that had been upgraded or built from scratch by the human elements fighting the Inhibitors. These ships were far more advanced than the average lighthugger, and were equipped with dark drives that emitted nothing in any detectable spectrum, miniaturized cryo-arithmetic engines which cooled their hulls to make it nearly indistinguishable — in thermal terms — from empty space, inertia suppression machinery that allowed extremely fast acceleration and deceleration, free-force bubbles which absorbed enemy attacks, camouflage screens that aided concealment, and extremely heavy armaments, including bladder-mines and hypometric weaponry.
- At the end of Redemption Ark the vast carrying capacity of lighthuggers is demonstrated by Ana Khouri and Triumvir Ilia Volyova as they load approximately 160,000 of the almost 200,000 on the world Resurgam onto the Nostalgia for Infinity.
- The full extent of a lighthugger's manufacturing capabilities is unknown, as they are only ever used in the novels to produce weapons. However, it is implied in Absolution Gap that the shadows' mass-synthesizer technology operated on the same basic principle, and there was little it could not build (up-to and including near-immortal robotic bodies).
- Despite Skade mentioning to Clavain in Redemption Ark that Conjoiners sold their drives primarily to the Demarchists and never directly to the Ultras, Sajaki of the Nostalgia for Infinity claims to Dan that if he blackballed him among the Ultra community he would be stranded in the Epsilon Eridani system indefinitely -- a statement Dan doesn't dispute, despite Dan being an influential man among the Demarchists. This implies that sometime before 2460 Demarchist society either sold or re-purposed their lighthuggers en masse.