Jameson Measuring Caliper, 95 mm – Inches and Millimetres

Dual graduation is what separates this from the metric-only calipers alongside it. Implant specifications, published techniques and instrument catalogues are quoted in whichever unit their source used, and a surgeon converting between them in theatre is introducing an arithmetic step into a measurement that was supposed to remove uncertainty. Both scales on one caliper means reading directly in the unit the plan was written in.

At 95 mm the instrument is short, which suits the confined work it is used in — the whole caliper sits in the hand and the tips move with the fingers rather than the wrist. The trade against a longer caliper is reach: this one measures what is in front of it, not what lies at the bottom of a deep exposure.

Specifications