I have had a PACT Model 1 for probably 15 years. It's only problem is that it must be set up so the shadow of the diffuser falls directly over the screens. If the ground is reflective like sand, I have to place a black blanket under the screens so it doesn't get goofy due to bullet glint.

If I had to do it all over again I would spend the money necessary to buy a higher end chronograph. An Oehler or Labradar would be on my wish list. Statistical analysis has become important to me with longer distance shooting.