If you do chose to buy The Shooting Chorny chronograph, I advise you to get some type of "shield" for the second sensor as people who are new to these type of chronographs tend to miss and hit the sensor and a high powered gun could easily destroy it too!
I had my dad pick a 1/4 inch thick piece of Teflon from Boeing as you can see in the photo below, I’m sure you could do this with a piece of aluminum or Plexiglass.
The white tubing you see is Spiral wrap, again people seem to always like to miss the sensor and hit the wire.
Spiral wrap is available at your friendly neighborhood hardware store.
As you can see in the picture below it is not glued in it is simply slightly bigger than it needs to be and is held in by the walls of the chorno pushing on it.
as you can see if that piece of Teflon was not there, I would buying a new chronograph!
And what’s the point of buying a Shooting chorny if you can’t fold it? The piece of Teflon is just small enough to lay flat above the 9v battery enabling the chorny to fold.
There's a difference between a person who has a screwdriver and a person who knows what they are doing.