Sale is for a vintage new Standard Motor Products DR-3X Ignition Coil as pictured.   "Blue Streak" is SMP's label for their premium quality line.  For 12V negative ground and external resistor applications.

Listed in SMP catalog to fit:

1955 - 1958    Chevrolet passenger models with V8 engine

May have other applications not listed.  Verify suitable for intended application as returns are not accepted.