You will need to know your WIDDER System1 or System2 Lectric-vest size in order to find your proper length in Lectric-ArmChaps™. Then measure the distance from the top vertebrae (the top bump on your backbone) to the elbow side of your wristwatch. If wearing no watch, measure to 2 inches above your wrist. This is where you will want the Lectric-ArmChaps™ to end. Using the chart below, intersect your vest size with arm length to arrive at the correct Lectric-ArmChaps™ size.     Arm Length as measured from top vertebrae to 2" above the wrist Vest Size 23 24 25 26 27 28 29 30 31 32 33 34 35 36 26 26 28 28 30 30 32 32 34 34       38 26 26 26 28 28 30 30 32 32 34 34     40   26 26 28 28 30 30 32 32 34 34     42   26 26 28 28 30 30 32 32 34 34     44   26 26 28 28 30 30 32 32 34 34     46     26 26 28 28 30 30 32 32 34 34   48     26 26 28 28 30 30 32 32 34 34   50     26 26 28 28 30 30 32 32 34 34   52     26 26 28 28 30 30 32 32 34 34   56       26 26 28 28 30 30 32 32 34 34