These are Karbonite gear servos. They have their place where servo loads are not real high and likelihood of flutter is low.

I use them on Ultimate ailerons because they are inexpensive and fairly accurate. The Ultimate's ailerons are small compared to a 28% monoplane because there are 4 of them.

The 6985s I used on elevator because they are accurate and strong enough.

I do NOT prefer these to metal gear servos, I still prefer the 5645 and 5945s, but I had them anbd they worked OK in this case.

TF