The Infiltrator Mk II is a Federated Suns (Federated Commonwealth when it was created) design that improves Star League-era technology to extend the capabilities of the successful Infiltrator Mk I.
         Though the AFFC was the undisputed leader in the early development of Inner Sphere battle armor, the sheer size of the AFFC prevented it from maintaining its' pioneering position. Forced to equip more line units than any other Inner Sphere power and simultaneously rebuild countless Regular Army regiments shattered or destroyed during the Clan invasion, the AFFC could not afford to expend the resources needed to maintain the same level of battle-armor development. While the NAIS and other military think-tanks kept abreast of the latest developments pursued by their rivals throughout the Inner Sphere, the AFFC's R&D funding dropped significantly as priority was assigned toward recouping losses.
         Not surprisingly, the further refinement of the successful Infiltrator Mk I battle-armor design came from outside the AFFC. The integral stealth capabilities of the Infiltrator Mk I made that design inherently suited for special forces and intelligence-gathering missions. Consequently, civilian and military elements of the Federated Commonwealth Intelligence Command (FCIC) provided orders for the Infiltrator Mk I that accounted for the majority of the Infiltrators built in the first few years of production. Within a short period of time the FCIC's Intelligence Secretariat directed its' Office of Science and Technology (OST) to collaborate with the NAIS on developing a replacement for the Infiltrator Mk I, tailored to the requirements of the FCIC's missions.
         The breakthrough technology for the new suit came in 3057, however, when the Intelligence Secretariat learned that the Gray Death Legion possessed several Mark XXI Nighthawk suits obtained from a Star League vault on Karbala. Grayson Carlyle, now Baron von Glengarry, had no choice but to comply with the Archon-Prince's request for the suits and by August they were en route to the NAIS, where engineers systematically dismantled them and analyzed their components. Though the Nighthawk suits were destroyed in the process, they provided invaluable data.

         The Mk II suit, dubbed the "Puma," surpasses the MK I in several ways. Faster, better armored and far more agile than the Mk I, the "Puma" includes an integral jump pack, an optional para-foil attachment for high-altitude insertions, increased stealth capabilities and electronic countermeasures. Designed to assume a more direct combat role than its' predecessor, the Mk II is fitted with two fully functional hands though one of the hands must be encased in a hardpoint when the Mk II is fitted with a support-class weapon. Although originally intended to mount the usual assortment of anti-Mech weaponry, the success of the Magshot Gauss rifle specially designed for the Mk II prompted the designers to include the new weapon as standard-issue on all Mk II suits. The Magshot Gauss provides Mk II troopers with a sniping weapon superior to any other on the battlefield.

         Primarily built and fielded by the nations once part of the Federated Suns, the "Pumas" are also used by Solaris and Proserpina. Outside of those governments, they are very rare and even more rarely seen.