An S-Spec Number (Sample-Specification Number), also sSpec or simply Specification Number, is a string of 5 alphanumeric characters that represent an exact IC batch (or set of batches). The S-Spec number can uniquely identify the model number (and all the specifications that go along with it) as well as the core stepping.

Production chips have an S-Spec number that always starts with the letter S. Qualification samples always have S-Spec numbers that start with the letter Q.