We’ve talked about the ST-1 Treatment a lot. That’s a permanent application of out Slipstream to the Bolt Carrier Group, Buffer, Spring, and Charging Handle.
The ST-2 treatment makes a huge difference. Because now you also get the trigger group, all the insides of the lower receiver, and inside the upper receiver. This is important because it slicks up the bearing surfaces where the bolt rides and he charging handle. Don’t get me wrong, ST-1 is worth it… but the ST-2 is on a whole other level. It blows other treatments, such as FailZero out of the water so hard, it isn’t even funny.