They are extremelly cheaply made and include no grommets and screws (at least I haven't gotten them).
Two out of 4 servos I've got are buzzing like crazy... The weight of 9g servos is closer to 11g.
I will put them in a simple foamy plane, wouldn' t risk a hely...

Basically, you'll get what you've paid for, which may be sufficient for not too demanding applications.

Just my 2 cents.
Boris