CM31640KITA - Aluminium Anode - for use in salt and brackish water.
Fits Mercruiser Alpha One Sterndrives & most Mercury/Mariner outboards 35 hp and above.
This kit contains:
• CM31640A X 1
• Mounting bolt X 1
...

Aluminum
Fits most Mercury/Mariner outboards 35 hp. & above and all MerCruiser except
Bravo. Check for adequate propeller clearance prior to operation.
Quicksilver Branded, Clamshell Package Point of Sale Packaged

97 31640Q 4 Mercury Aluminium Anode
Additional Details:
Material: Aluminium
Fits: Most Mercury/Mariner O/B's 35hp & above and all MerCruiser except Bravo
Use With:
18-6245: Anode Mounting Bolt
For more...

CM31640KITM - Magnesium Anode - for fresh water only. Not recommended for salt or brackish water. 
Fits Mercruiser Alpha One Sterndrives & most Mercury/Mariner outboards 35 hp and above.
This kit contains:
• CM31640A X 1...

Aluminum
Fits most Mercury/Mariner outboards 35 hp. & above and all MerCruiser
except Bravo. Check for adequate propeller clearance prior to operation.
Mercury Branded, Clamshell Package Point of Sale Packaged.

• Anode
Additional Details:
• Fits: Most Mercury/Mariner O/B's 35hp & above and all MerCruiser except Bravo
• Material: Zinc
Interchange:
Mercruiser Stern Drive
• 31640
• 316404...

• Anode
Additional Details:
• Fits: Most Mercury/Mariner O/B's 35hp & above and all MerCruiser except Bravo
• Material: Aluminium
Interchange:
Mercruiser Stern Drive
• 31640
• 316404...

• Anode
Additional Details:
• Fits: Most Mercury/Mariner O/B's 35hp & above and all MerCruiser except Bravo
• Material: Magnesium
Interchange:
Mercruiser Stern Drive
• 31640
• 316404...