1/16 scale early M3/M4 Bogies. These are to modify the Heng Long M4 bogies into an earlier type.
Here's the instructions on how to fit them (these were an early test version -
http://warrenhudsonmodelling.blogspot.com/p/m3-bogies.html
The fake springs only go a certain way depending on which way round the spring is on the HL bogie, so you need to test fit them before gluing the pin into place.