Look for explicit TSA, checkpoint, or clear-bag policy compliance on the product listing, transparent construction that clearly shows contents, and sizes/styles marketed to meet airport security checks or venue clear-bag rules—these features help speed screening.
One example lists a transparent PVC backpack sized 16" H x 5" W x 11" D with a 30‑liter capacity and specifies it meets Clear Bag Policy or checkpoint requirements; sizes and capacities may vary by model.