Lumen Farm 4" and 6" Inline Fan Lumen Farms $152.99 4 Inch - $152.99 6 Inch - $167.99 Quantity This variant is currently sold out Please fill in the form below if you'd like to be notified when it becomes available. Lumen Farms 4" and 6" inline fan with a leather sheath and variable speed controller. Designed for quiet operation, long life, and incredible durability.