Attributes and variables sampling plans are widely used in inspection for the purpose of acceptance or rejection of a product, based on adherence to a standard. Attributes sampling plans are used for those quality characteristics are expressed on a ‘‘go, no-go’’ basis and variables sampling plans are used for those quality characteristics are measured on a numerical scale. Variables sampling plans based on the measurement process rather than the labeled the product in good or bad so provide more information than the attributes sampling plans. Further, variables sampling plans would require less sampling than attributes sampling plans to reach the same protection. Therefore, variables sampling plans attracted the more and more attention of industries now. However, the traditional attributes and variables sampling plans cannot deal with the lot sentencing problem very well when the process fraction of defectives is required very low with two-sided specification limits. To remedy for this, several variables sampling plans based on process capability indices (PCIs)