R4-499RAT 4 Inch Non-IC Airtite Remodel Housing is made of aluminum and adjusts up to 1.75 inch ceiling thickness. Non IC designation requires that a minimum 3 inch clearance away from insulation should exist on all sides of housing. Airtight feature prevents airflow between attic and living areas. Meets restricted airflow requirements. One 50 watt 12 volt GU5.3 MR16 halogen lamp or LED equivalent is required, but not included. Supplied with a low voltage magnetic transformer. Halogen dimmable with a low voltage magnetic dimmer. LED dimmable per lamp manufacturer recommendation. Must be dimmed using a low voltage magnetic dimmer. ETL listed. 4 inch diameter opening x 5.5 inch housing height. For use with R4 4 Inch GU5.3 MR16 compatible trims, sold separately.