This is the  speed reducer kit for the Jet 20" planers.  Replace the lower drive gear and chain and this will reduce the feed rates to 16.2 feet per minute and 20.7 feet per minute. This compares to the standard 24 fpm and 31 fpm rates.  You'll see the most improvement if you have the 4 knife head machine.  The bore on the new sprocket is 17mm.   Shipping on this item is free via USPS or UPS. I do combine shipping wherever possible. I do ship internationally. Just email me and I will quote shipping to your country.