10" x 4" Floor Register HVAC Air Supply Grille - Heavy Duty Rigid Built - Plastic Never Rust Vent Duct Cover [Outer Dimensions: 12w X 6"h] 18" Round Duct Pipe Its smooth

Its smooth

Our coils have a a very high PSI burst pressure

Slots are angled to diversify the airflow in 2 way direction

The first number in a grille size represents the width

Works for all Air Conditioning applications including Ductless Mini-Split

10" x 4" Floor Register HVAC Air Supply Grille - Heavy Duty Rigid Built - Plastic Never Rust Vent Duct Cover [Outer Dimensions: 12w X 6"h] 18" Round Duct Pipe Its smooth10"w X 4"h Is The Size For The Duct Opening Measurement Only, Actual Front End Outer Dimensions Are 12" Width X 6" Height SEE IN DESCRIPTION HOW TO MEASURE A GRILLE Solid Construction Designed For Floor Use High Quality ABS Plastic Will Last Forever & NEVER RUST Foot Operated Opposed Blade Damper For Full Air Flow Control And Shutoff Multi Angled Fan Pattern Fins For Multi Directional AIr Distribution Throughout The Entire Room 10" x 4" Floor Register