These are replacement eccentric rods Crank pins for  Minitrix A3 (4-6-2), A4 (4-6-2), 7P (4-6-2 Britannia), 9F (2-10-0), US K4 (4-6-2) and US Decopod (2-10-0) steam locomotives.

These are a direct replacement for the original and can be fitted without removing the metal rivet.

They come in a pack of 8 and is are available here.

You can find a post about replacing the crank here and an update here.

The kits are printed in the Shapeways FUD material which will require cleaning upon delivery, please see my FAQs for more information.