I have two Caliber III's in my humi and they're always within 1% RH of each other. One's in the bottom, the other the very top. Unlike the IV's, the III's can't be calibrated. But from what I've seen, they don't need it at all. They've consistently kept the same for about 3 or so years now and I'm quite happy with them. I had bought a Xikar one before the Caliber's and it didn't work right. They (Xikar) replaced it and the replacement was just as bad so I actually threw that one out....lol.
I almost bought some Caliber IV's because they can be adjusted but my III's are still working just fine so there's no point. I admit though, I didn't like that they weren't adjustable but over the course of the first year I had the III's I tested them several times to ensure they were accurate and they were/are.
I've had two different analog hygrometers (came with the humi's) and neither one was worth the gun powder it would take to blow them to pieces.
Welcome to the board Twotacotuesday.