Made from Raw Brass these provide an alternative to the usual etched coupling rods. No solder lamination is needed unless desired for either extra strength or 'painting'. The holes have been made small to allow you to ream or drill them out to the correct working clearance, depending which Crank Pins you are using.
These have been designed to work easier with Alan Gibson's Crank Pin system as test builds proved the older design of Coupling Rods (formerly available - please ask if you still want them) had to have the Bosses thinned out a lot leaving them very weak.
As with real life different rods were different thicknesses. You may want to file the rods themselves slightly thinner so the retaining nut can home in on the bush easier, or use one of Alan's longer bushes, or do as I often do and use a little superglue to fix the nut slightly further away.