The T-103 is a mass-produced variety of Tyrant produced by Umbrella in 1998. They are modified clones of the T-002 developed at the Arklay Laboratory, improving upon its qualities. By improving the T-103's metabolism over the T-002, cellular regeneration was improved, allowing them to quickly regenerate from injuries they sustain during combat.[excerpt 1] However, should T-103's sustain heavy amounts of damage, not only do they regenerate but they also begin to mutate, most likely as an adaptive response to the extensive trauma they have received.
These regenerative mutations are why most T-103s were provided with "power limiters", which are devices intended to prevent any further mutations. In the event of a serious injury, this device would be de-activated, allowing the T-103s to undergo drastic regenerative mutations and rapidly evolve into their so-called "Super Tyrant" forms.
A second quality was that of their intelligence. While the T-002 was himself near-human intelligence, he was resistant to orders. The T-103 series was designed in part to correct this flaw and, consequently, they are expected to obsess over carrying out their mission. During the Raccoon City Destruction Incident, "T-00" was shipped into the Raccoon Police Station with orders to kill everyone inside, obtain a locket known by Umbrella HQ to contain a Golgotha Virus sample, then return to a designated pick-up point. T-01, T-02, T-03, T-04 and T-05 meanwhile were sent to Incineration Disposal Plant P-12A, where they perished in battle with Delta Force, refusing to retreat.
The third alteration was more external in nature. Considering the viability of B.O.W. infiltration, the T-103 clones lacked large claws and other distinctly inhuman traits, and were typically dressed in clothes to blend in.