I've included the serial numbers so that you can check them out yourself. The first one is a 2017 model and all the rest are 2012/13. The specs are included, as are some issues we've had with the three older models. If you know what you're doing, I'm sure you could get them to reinstall an iOS, but it wouldn't be the latest version. Otherwise, they would be great for parts.
C02WJ21LH7JY
Running Windows 10
iMac 21.5-inch, Late 2012
8GB RAM
1TB Internal Storage
2.7 GHz Intel core i5 processor