Review on Enhance Your UNO R3 with the HiLetgo 5V 4 Channel Relay Shield: Efficiently Control Four Channels by David Hashman

In general, everything is fine. However, it is important to note that if you slide the relay board all the way to the Arduino. All three solder connections for Relay 1 make contact with the Arduino's USB header. If you want to use this relay I would put some kind of insulator between the USB connector and the solder joints. This board will still work fine for me, but I think this is an important detail to pay attention to due to the safety issues this can cause.