MG Duff Aluminium Shaft Anodes  25mm, 1", 30mm.  For salt and brackish water use only. The ASA range of shaft anodes are well known for their quality, and classic golf ball shape. This range of shaft anodes are an excellent way to protect your shaft from corrosion. The electrochemical capacity is more than 3 times higher than of the same mass of zinc (you can protect more with less) Aluminium anodes carry a better environmental footprint than zinc anodes. Aluminium anode alloys do not contain cadmium, which is harmful to the marine environment. 25mm Anode: Diameter 25mm ø: 55mm ø1: 25mm h: 55mm Weight: 0.150kg 1" Anode: Diameter 25.4mm - 1" ø: 55mm ø1: 25.4mm h: 55mm Weight: 0.15kg 30mm Anode: Diameter 30mm ø: 61mm ø1: 30mm h: 61mm Weight: 0.190kg