Additional upgrades were made to the model's power unit, which consisted of two hydrogen fuel cells — this added redundancy in power generation that wasn't present in earlier models.

Skynet's most well-known products in its genocidal goals are the various terminator models, such as the T-800 (Model 101).

Skynet decides to send the new Terminator model, the T-X into his present to kill other top members of the future Human Resistance, while the Resistance sends T-101 which is a reprogrammed T-800 ...

The Rev-9 wasn't made by Skynet, as it didn't exist in the Terminator: Dark Fate timeline. Instead, humanity came to blows with Legion. In many ways, the Rev-9 is two Terminators for the price of one.