These com in handy for all sorts of servo install's* true some servos may not be compatible but I have found that it is better to have an option than not, it's always good to have some extra parts around if and when you need them.
Sally that is a good question. I remember when every servo had the fitted. Back most planes flew with petrol engine which vibrate a lot more than the brushless motors we use today. So the answer is you can get away with them on most park flyers but if you use an engine please use them. I hope this helps
Fit the rubber grommet in the servo ears, then insert the metal eyelet so the flared part is ***between the servo and the servo tray***.
This will prevent over-tightening which will not only damage the wood, but also over-compress the grommet, reducing or completely eliminating vibration isolation.
Basically, I hate servos with a big hole in the mounting tabs. But I got some of those in my spare parts box, and the only way to use them, is with these grommets. So 5 stars for the grommets, otherwise I would have trashed the servos...