Duo-Fast CN350 O-ring and Cylinder seal Kit on ebay, $14.95 Free Shipping.
$14.75 here with free shipping, Same seller, same service, lower Price.

Duo-Fast CN350 O-ring + Cylinder Seal CN-220-3
Duo-Fast CN350 O-ring + Cylinder Seal CN-220-3
CN350 O-ring Kit + Cylinder Seal #cn-220-3
Schematic + O-ring Reference Sheet
Price includes shipping in the US
Available Qty: 14