This is fun 
It's a 1.5nF 400V AC, 4kV AC test, Ceramic. Note that while it's certified for flamability, it's not suitable for use (unprotected by a fuse) across the mains as it doesn't have an X or Y marking.
Edit: Y2 would require 5kV test and Y1, 8kV.
The markings say it has mains use approval for Switzerland, Sweden, Germany, US, GB, which then automatically leads to approvals for other countries, generally all of the EU. It's approved for Y and X1 use.
It's ceramic and older than 1994, where the approval markings changed (X or Y specifically marked on the part).