RE: [Demo notebook] QC clinic: photographic evidence and its limits · RWI-01385

Case 27 — Strap dimensions: lug width, taper, thickness and spring bar diameter explained

I want to buy aftermarket straps but keep seeing 20/16, 22mm, 4mm thick and spring bar sizes. Which measurements do I actually need to take from my watch, and how do I measure them without the right tools?

Exercise RWI-01385/27: address this question within its stated limits.