bear.1216 9/4/2013Can you describe the part or upload a picture. Is it a tool or auto part. There is a spark tester with that name looks like a spark plug with clip attached used to check for spark by attaching plug wire to one end and clip attaches to engine ground. You then turn over vehicle and look for spark. There is also a spark master ignition module. Hod rodders used this part to change spark timing on high performance engines for smoother idle and prevent detonation with nitrous oxide. Post picture and description online for more help.
Jimm 9/5/2013That is a 'spark gap' spark plug tester. Coil ignition systems rely on the buildup of voltage in the secondary to a point that it will jump the gap in the spark plug - when the points are opened inside the distributor.
If there is a fouled plug or some other lower resistance path to ground then the voltage in the secondary would not build, instead draining off through a path of lower resistance. Putting a 'spark gap' on the coil allowed the voltage to build to a point it would jump the spark gap and being in series with the spark plug it would most likely jump the plug gap also. They also used to sell these at the local fairs.