Two extension rings for sale: Sea & Sea 40 mm and Sea & Sea SX (approximately 20 mm). Perfect condition. Switched to a Nauticam housing; so these are now available.
Both extension rings for $250 including shipping in US. Paypal.
40 mm extension ring by itself $175 US including shipping US (289 new)
SX extension ring: $125 US ($189 new) including US shipping
Will ship overseas, but buyer pays shipping.