Select options 4″ x .024 Aluminum Smooth Round & Corrugated Elbows $3.75 – $4.50 Smooth elbows will have one end expanded for ease of installation. Our Aluminum Elbows are available in several Standard Colors (smooth and corrugated styles) and Select Colors in smooth style. See Color Chart below. We can also produce Select Color corrugated elbows for a $100.00 up charge per order. 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 3″–9″ offset; 72 degree elbows have a 9″ 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 9″ will require 2- 72 degree elbows. If your overhang is greater than 9″ you’ll need to insert a piece of downspout between the elbows. An overhang of less than 9″ will require (2) 40 degree elbows. This elbow combination also works when making a transition around a ledge or other protrusions. You’ll need to reduce the size of the opening on the elbows and downspout when using either corrugated or smooth options. (see Product Description below left and our Elbow & Downspout Crimper Tool.) Note: Smooth elbows will have folds in the bend.