This kit contains everything you need to convert your Impulse to use a low pressure regulator. Using the LPR kit gives you the ability to separate the solenoid pressure from your firing pressure. The results are a big increase in gas efficiency and no more bolt stutter. The included Smart Parts' Reg is one of the most reliable around. The included spring caps are all black. The Smart Parts' Reg body and tape worm cap are color matched in either Black, Red, Chrome, or Blue.