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

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.

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.

Not Metal Gears. Strip easy if it works at all. So far I've tried 4 different servos out of the 12 I got and 2 were defective and non functioning while the other 2 stripped almost immediately after putting them in my plane. If you are expecting metal gears don't be fooled by these they are just plastic.

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.

These are not great quality servos. From my experience they have about a 5-10% DOA rate, and they also do not last as long as higher quality servos, even if they are not DOA. However, they are cheap as heck. If you need a bunch of cheap servos to do the job of cheap servos, this is a fine deal. $1.58/servo is throw-away money, but these are throw-away servos, you get what you pay for. If you want high-quality, precision servos for critical applications or use in twitchy or valuable flying models, look elsewhere.

Cannot go wrong with metal gears. Use these in my foamie airplanes. Good price.

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.