Product details:

VanEssential Magnetic Insulated Roof Vent Sun Cover for MaxxAir Fan, Fantastic Fan (Charcoal Gray)PROP 65 WARNING: This product can expose you to some kind of chemical, which is known to the State of California to cause cancer.Compatible with MaxxAir Fan or Fantastic Fan 16.5 x 16.5 flanges
Made with 5.0mm double foiled aluminum PE insulation which reflects up to 97% of radiant heat
Uses powerful N48 Neodymium magnets to hold in place
Made from 100% recycled PET plastic bottle fabric. Storage sack included