Saw this for the first time in this month's Wood magazine.

http://www.grip-tite.com/splitter.html

To see what it is they are actually referring to go here.

http://www.homestead.com/ValRoseWoodWorks/Splitter.html

My first thought, after thinking I'd have to re-write the
instructions for making a zero clearance insert was, Hey!,
This guy stole my idea for doing up a super fine zero
clearance insert Web page!

Please, go back to your houses.

UA100