KNEW CONCEPTS FRET SAWS
Wonderful saws made from rigid aluminium, when you aim them straight they cut straight! Great for removing the waste from dovetails.  
In the US the saws are available from http://www.highlandwoodworking.com/david-barron-tools.aspx  
For the rest of the world please contact Classic Hand Tools https://www.classichandtools.com/acatalog/Knew-Concepts.html