The Defelsko Posipen and Positest coating thickness gauges are ideal for checking chrome thickness on hydraulic cylinder rods.
The Hydraulic Troubleshooting App is a nifty tool to keep on your phone or tablet, so you can refer to it when needed. And you will need it at some point, that's for sure.
It's FREE. And it's available for download now from Google Play and Apple's App Store. So get yours today.