A lightweight 3D-printed hat conformer that measures head circumference with precision. Adjust the fit by turning the wing nuts to expand or contract the ring. Suitable for head sizes approx. 18–24.8 inches Fits standard hat sizes US 5 3/4 – 7 7/8 The golden center key marks the exact middle for easy alignment when drafting patterns or checking symmetry. A reliable tool for milliners and hat makers who need accurate, repeatable sizing.