Stainless Steele Ducting Clamps - Lumen Farms Lumen Farms Growing $1.25 4 inch - $1.25 6 inch - $1.49 Quantity This variant is currently sold out Please fill in the form below if you'd like to be notified when it becomes available. 4 inch and 6 inch stainless steele ducting clamps by Lumen Farms.