12PCS SG90 Micro Servo Motor, Dorhea Mini Servo SG90 9g Servo Kit for RC Helicopter Airplane Car Boat Robot Arm/Hand/Walking/Servo Door Lock Control

I purchased these servos to drive wheels in simple robot projects powered by microbit controllers. Found lots of projects online that use 360 degree continuous servo motors to power wheels, etc, these were perfect for my purpose, and at current prices due to global trade issues, these were available for a reasonable price.Also, at least the top gear on these servos is metal, and threaded to take a 2.5 mm small bolt.Very happy with purchase.

A lot of people mention there are plastic gears inside, but the main gear is metal—and that’s what matters. I’ve been using these in some of my 3D printed projects, and they’ve taken a beating and still keep going. Solid performance, no complaints so far.

Used these in a ground based (thankfully) project. 12 servos. 4 plugged into the board overloaded the 3 amp buck converter at an idle. Found some the pulled too many amps. A few completely dead. Some get hot. All are extremely weak. Your milage may vary, but there is no way i would purchase these again for any purpose let alone in a flight application. Of the 12, 5 are still in project. They are getting cycled out as i write this. Consider Miuzei instead. So far they are working smoother. On teardown they are not even MG90 servos. All gears are plastic but the one you see on the outside.

These are typical, no better or worse than others. All 12 that were shipped work perfectly.I do like that the plastic gears will tolerate a bit of "grinding" if the load is too heavy, but otherwise these are typical but very good for the price.

Beware - if you are a DIY custom builder, these new servos can no longer be “wire reversed”. You’ll have to buy a separate signal reverser if you want your servo to run “backwards”.

Although many people are saying there are some plastic gears in there, the main one is metal.It has worked well for my RC plane projects, and have taken a beating, but still work just fine.

Good little servo for the price

Let's just address the obvious issue on these servos..... I believe that most folks purchase these with the assumption that it is a metal geared servo.... it's not. The only metal gear is on the output, the rest are gray plastic (you can see in the picture that I included). If you need these for a project that will put stress on the servo, do not use these. I had these in a delta wing RC plane and stripped 2 of them out just belly-landing into grass (no huge impact, just landed and the servos started making the classic whirring noise).For the price, they are adequate. You can't expect much out of a servo that costs $2.70 a piece. I have been using these in lightweight, foamie RC planes and they get the job done. However, any sort of hard landing or crash has stripped out at least one servo. I would not use these in anything that has higher value. They are pretty quick and have decent torque for their size. The output will rotate 180 degrees by hand, but I could not get them to go more than 90 degrees when hooked up to power.I've ordered 3 batches of these servos and at least 10% of them didn't work right out of the box. I managed to fix them by resoldering the wires (it's a tiny spot and not easy to do).Overall, these work great for cheap-o RC planes that won't be flying fast or high. They still get 3 stars in my book because they're very inexpensive and they do work..... they just aren't true metal-geared servos.