Light straight run naphtha is a type of light naphtha that comes from  distillation cut comprised of pentane and slightly heavier naphtha range material. 

Light naphtha can come either from crude distillation or from fractionation of NGLs (natural gasoline).

The light naphtha distillation cut has three typical uses:

• Blending directly into a finished light naphtha product

• Feed to the isomerization unit to make isomerate for blending into gasoline

• Direct blending into gasoline

As a blend stock for making gasoline, light naphtha is of fairly low quality. It tends to have low octane and high vapor pressure. So it typically only makes up a very small portion of the gasoline pool.