SmartFly Tech CO. from AliExpress are SCAMMERS!
I bought two encoders, one of which turned out to be defective. The price for each one is $150. I contacted them and they told me to send it back to them and then they will send me a new one. I sent it and a month later I wrote them a message to check if it had arrived back to them. I was told that if had arrived, but they had to check it. I have been constantly writing to them for the last five months. They read my message but they did't reply me back.