Wondering what the NoInstallClass registry setting is? NoInstallClass is set in the registry to tell Windows that devices of a particular type (listed in the registry key class hosting the NoInstallClass setting), that users should not see this type of hardware in the Device Manager.
You would only set NoInstallClass to a value of 1 if no device with the NoInstallClass setting will ever require manual installation from users. In other words, these devices should only be plug and play. Alternatively, you might set the NoInstallClass registry setting for devices that users should not be able to install, where they do not have a driver; Though I am sure there are probably better ways to do this.