12"x 8" (Duct Opening Size) 2-Way Stamped Face Steel Ceiling/sidewall Air Supply Register - Vent Cover - Actual Outside Dimension 13.75" X 9.75" The Listed size 10"x 6"

The Listed size 10"x 6" is for inside duct opening measurement

it refers to the size of the "tongue"  so that it will fit in a 8"x8" hole

Built in magnets on each side for easy installation

Duct opening – a hole that holds the duct neck to allow air to come out from HVAC system

12"x 8" (Duct Opening Size) 2-Way Stamped Face Steel Ceiling/sidewall Air Supply Register - Vent Cover - Actual Outside Dimension 13.75" X 9.75" The Listed size 10"x 6"Durable Construction: This air supply register is made of sturdy stamped steel for long lasting use and reliable performance. Versatile Application: Designed for ceiling or sidewall installation, this vent cover can be used for air supply in various residential and commercial settings. Efficient Airflow: With a 12" x 8" duct opening size, this register allows for optimal airflow distribution from your HVAC system. Easy Installation: The actual outside