Made from billet aluminum, they are enhanced by a combination of 3D machining and a perfect Harley-Davidson® style gloss finish. The AZ021 Riser Kit , diameter 31.8 mm, gives a riding position 10 mm higher and 10 mm further back than OEM risers. Made from billet aluminum, they are enhanced by a combination of 3D machining and a perfect Harley-Davidson® style gloss finish. The AZ021 Riser Kit , diameter 31.8 mm, gives a riding position 10 mm higher and 10 mm further back than OEM risers. Made from billet aluminum, they are enhanced by a combination of 3D machining and a perfect Harley-Davidson® style gloss finish. The AZ021 Riser Kit , diameter 31.8 mm, gives a riding position 10 mm higher and 10 mm further back than OEM risers.