A fast drying filler/putty available in Grey and White.
Common Question: What’s the difference between the grey & the white?
Answer: Colour. That’s it. The idea is that you use the colour that offers a contrast to the colour of the model you are applying it too. This is so that as you file, flat and wet & dry it to shape you can see that you are creating a nicely feathered edge between the model and the filler.
They used to do this in Green. Grey is the new Green