A slab is the sealed acrylic case used by third-party grading services (PSA, BGS, CGC, SGC, PCGS, NGC) to encapsulate certified collectibles after grading. The slab includes the item, a tamper-evident seal, and a label showing the grade, certification number, and item details. Slabs provide both authentication and physical protection but cannot be opened without breaking the seal. Cracking a slab refers to removing the item from the holder, typically for resubmission.

Slab is collector slang for the tamper-evident plastic case that third-party grading services use to encapsulate authenticated and graded items. The case typically consists of two halves of clear acrylic ultrasonically sealed around a plastic insert that holds the card, comic, or coin in place, with a printed label inside the case stating the grade, certification number, and other identifying details.

Slabs serve three functions: they prevent the item from being tampered with after grading; they establish provenance through the certification number lookup; and they protect the item from physical damage and environmental exposure. Slabs are not airtight, however, and can develop internal condensation if moved between extreme temperatures. Long-term slab storage benefits from climate-stable conditions and from purpose-built slab boxes that prevent the cases from sliding against each other. See grading scale for what the printed grade on the slab label actually means.