Select options 4″ x 16 & 18 oz. Copper Smooth Round & Corrugated Elbows $12.00 – $17.25 Smooth elbows will have one end expanded for ease of installation. The average installation requires two elbows at the top and one at the bottom. If you are connecting your downspout into a drain tile, the elbow at the bottom is not necessary. The offset is the measurement of two connected elbows. 40 degree elbows have a 2″–7″ offset; 72 degree elbows have an 8″ offset. The degree of elbow you use is determined by the overhang of your structure. To determine the overhang, measure the distance between the wall of your building and the back of the outlet. An overhang of 8″ will require 2- 72 degree elbows. If your overhang is greater than 8″ you will need to insert a piece of downspout between the elbows. An overhang of less than 8″ will require 2- 40 degree elbows. This elbow combination also works when making a transition around a ledge or other protrusions. You will need to reduce the size of the opening on the elbows and downspout when using either corrugated or smooth options. See Installation Tips under Product Description below and our Elbow & Downspout Crimper Tool.) Note: 16 oz. smooth elbows will have folds in the bend; 18 oz. welded seam smooth elbows are completely smooth. Also available in 16 oz. lead coated copper; please call 269.665.2700 for pricing.