The Series 900 is a type of Terminator mass produced by Skynet. The T-900 is Skynet's follow-up to the Series 8xx. It was a cybernetic organism — living tissue over a hyperalloy-armored endoskeleton.
With rogue Terminators increasingly reprogrammed to help the Resistance and the Resistance can produce their own terminators, Skynet decided to make a Terminator series with the intent of terminating other Terminators. The T-900 series was twice as fast, strong and durable. Its battle chassis was covered with hyperalloy armor and had many choices of vision. The T-900 is powered by a miniature plasma fusion reactor in its torso, making its body glow in certain color. It has the ability to drive animals to the point of attacking their own handlers.
However, in this story, some of T-900s are covered with special cybernetic organism living tissue but we had never seen them in this form. In the script, it mostly explain them as a "T-900 endo".
The T-900 has the same style power sources as T-850's, they were designed to use the thing call "Power pack" protecting the inside main sources, a pair of hydrogen fuel cells. And beside, this model can be shocked by electric and can't be turned into reboot stage in ease like the older models. They also can't be re-programmed like the redesigned T-888s.
T-950 is the main units which traveled back in time to change things after TSCC story. This model differ T-900 by its strength, speed, and fast healing special cybernetic organism living tissue like the mutant human from X-Men, Wolverine. However, only two ways to stop them are blasting the chip and pulling out the "Power pack".