Okay, so if you're into precision measurement—like, really into making sure your coating thickness gauge is spot on—then this YUSHI foil set is exactly what you need.

It's brand new, still in its original packaging, and comes with 12 different foils ranging from 10 all the way up to 6000 micrometers.

That's a huge range, so whether you're measuring thin paint or thick industrial coatings, you're covered.

These are essentially precision gage blocks, but in foil form, made for calibrating your equipment to make sure every reading you take is accurate.

They come from China, the model is straightforward (10-6000μm), and they're bundled together in this nice set with the MPN A-203-0001.

YUSHI is the brand here, and they're pretty well-known for this kind of stuff.

The UPC is 611702795332 if you need to look it up.
Basically, if you're a quality control tech, a lab nerd, or just someone who takes their coating measurements super seriously, this set is a must-have to keep your gear honest.
Don't trust a reading unless you've calibrated with something like this first!
