All arm-sizes can be fitted with a Knockstop ®. Both U-shape bent, strips can be firmly attached together on both ends, using two tie wraps or four nylon blind rivets 3/16" . The correct position for fastening the strips is attained when the middle of the overlapping region is near the inner side of the elbow. See the figures below. Choose the correct size by measuring the elbow circumference/diameter.
For more safety preferably two holders must be used.