Hello there, thanks for giving us time to share your feedback with us about the Nest Thermostat Trim Kit, and we’re sorry to hear it doesn’t fit your Nest thermostat.
The Nest Thermostat Trim Kit (oval) is intended for Nest Thermostat only and it’s not compatible with Nest Thermostat E and Nest Learning Thermostat. That said, we’d be happy to help and guide you with installation if you can tell us more about your concern, or you may see this link for more information about installing a Nest thermostat trim plate: https://support.google.com/googlenest/answer/10151466
For assistance, our dedicated team is always available to help you here: https://support.google.com/googlenest/gethelp