Each Spring Probe has its own stroke, determined by the length of the barrel and the shape of the plunger.
Basically a Spring Probe has:
When the Spring Probe is not subject to any pressure; in this situation the total length of the article is defined, with a spring preload given during assembly.
The travel that the plunger can take before reaching one end of the barrel and during which the spring is subject to greater stress.
Also called operational stroke; it is 2/3 of the total stroke, and indicates the maximum movement that allows to avoid stressing the spring. If this value is respected, the spring will last longer.