Used Carter # LGL100A Laser Guide Line Light
Turns on and works. These came from a company that had a lot of rip saws and had a few extra lights on a shelf. The serial number on the light and the one written on the box do not match.  
 
The power indicator light on the back flickers but the laser light seems ok.
I do not know much about these sold as is.
 
 [Please Look at all the pictures they are part of the description]
 
  This is from a now closed factory that kept spare parts in stock for their equipment boxes / parts may have some shelf wear, dust / dirt.
 
                                                                    [B1-F1-R6-S1-3]