Universal 1/32 DIN PID Temperature Controller
[SYL-1512A]

We have used several of these units to replace older bi-metal controls in laboratory incubators.
With a bit of tuning the offset we can keep the sample chamber at 41°C with just a 0.1°C drift. It doesn't get any better for the money!

We also use 4 of them, only as thermometers, in a test setup for a product we fabricate. So far all units have been operating without any issues.