This product is very well built and should last forever. The gears are smooth although they do require more effort to turn than I would have expected. This is probably due to the fact that the spring that allows the user to override the gear is very strong.
Mine arrived with a defect in the plate that holds the camera. When I turned the screw to loosen the plate, it stuck. I hoped that tightening and loosening it and forcing it open with my hands would fix it, but it didn't. I applied WD40 but that didn't help. Finally, I contacted customer service via their website. I received a response within a few hours asking me to provide them with my order number and to supply a video that illustrated the problem. I created a video with my phone, uploaded it to Dropbox and sent the link to customer service. I promptly received a message that the product was defective and that they would send me a new one.
The company is located in China and it took about 3 weeks for the new one to arrive. I've checked it over thoroughly and it functions as expected.
This was outstanding no-hassle customer service. I'm happy to recommend K&FConcepts for the quality of the product and the customer service.