As hc225 mentioned, from experience in the industry, AQL levels are in place for the critical dimensions from the technical drawings of the product. Quality Control (QC) measures are conducted for every batch of product. As I have experienced with a Class I medical product in the US, but a Class II medical product in EU, sample size per QC test is also dependent on risk as mentioned by hc225. And the acceptance rate of each QC test is also dependent on risk. Large sample sizes for these test can be very costly since it is conducted per batch of product during it’s entire lifespan in the marketplace. And if QC tests are added or removed due to presence of failures, cost, necessity due to risk, then it will require registration notifications and possible re-registration depending on the type of changes and the effected markets.