These are possibly the best vibration isolation foams available.  Highly absorbent to vibration on your helicopter, multirotor (quadcopter, hexacopter, octocopter, etc)or airlpane, these foam squares will keep any flight controller or gyro free of excess vibration!  These foam squares are 10mm by 10mm by 5mm thick.  In most cases, only 4 are needed per device.  Adding more than 4 squares will NOTreduce vibrations, it will actually increase them, so only use 4.  In some cases your flight controller might be too light and you will benefit from adding some extra weight to the flight controller before adding the foam squares.  These foams squares are double sided and will stick to nearly anything. Much better than the thinner foam sheets that most places carry for the same purpose.  Try it and you won't be disappointed.

We use these same foam squares on all our high end Pixhawk based quad/hex/octocopters and the vibrations are always within +/- 1g, which is WELL within the recommended +/- 3g range.

This listing includes 12 foam squares!  Each is 10x10x5mm.  This is enough for 3 flight controllers or Gyros.