Europe’s rearmament argument is conducted at the level of platforms and prime contractors, because that is the level at which budgets are voted and contracts are announced. The constraint, when it appears, tends to sit several tiers below, in components whose defining characteristic is that they cannot be described by a drawing alone. A precision ball bearing for a stabilised sensor is one of those components. Its dimensions are public and unremarkable; what makes it the part that works is a combination of ring and ball materials, cage design, lubricant, preload, tolerance class and measured friction torque, established between supplier and customer during study and quotation and then held constant by a manufacturing and inspection régime. Because that combination is commercial and contractual rather than geometric, the question that matters strategically — whether the availability of a European sensor depends on one supplier’s ability to reproduce it — is precisely the question that public documents are least able to answer. This analysis takes a firm where the temptation to answer it anyway is strong, and separates what its filed accounts and published documents establish from what they do not. The company is A.D.R., a bearing manufacturer at Thomery in Seine-et-Marne whose own material places it in airborne electro-optical systems, terrestrial sights and missile seekers, and whose 2025 accounts describe a business running below the capacity it says it needs while orders accelerate. The answerable question is how such a firm converts bespoke engineering requirements into repeatable output, and what constrains the expansion of that output. The unanswerable one, at least from the record examined here, is whether any identified European optronic system depends on an identified ADR bearing whose replacement would require a defined requalification.