[refurb]

They are typically harden steel, so wear minimally and when you test a gap, you’re not really applying much force.

If the feeler gauge doesn’t slip in with minimal force, then that tells you the gaps is smaller than the gauge.

[teh_klev]

> If the feeler gauge doesn’t slip in with minimal force, then that tells you the gaps is smaller than the gauge.

The numbers of sets of comically bent out of shape feeler gauges I've encountered in my life demonstrates that there's a bunch of folks out there who don't understand how they're supposed to be used. As in "maybe if I just push harder this'll fit" :)

[refurb]

It’s a combination feeler gauge/pry bar!