This is a short video of Mike Hughes explaining a little about the S.I.R.T. Pistol. Mike is the founder of Next Level Training and the creator of the S.I.R.T Pistol.
What some of the "experts" say;

"Using a SIRT Pistol, the "trigger take up" laser allows the shooter to gauge the smoothness of his trigger control, and another laser “marks the spot” where the shot would have gone when the sear releases. Useful for solo practice, it will be particularly valuable for “coach and pupil” dry-fire training."
Massad Ayoob
Massad Ayoob

"The SIRT is an extremely valuable tool for training CCW applications. You can safely practice your draw from new clothing configurations before you hit the range. With the SIRT, you can also train in unorthodox shooting positions which may not typically be permitted at your typical indoor range."
Hilton Yam
Hilton Yam