How to send something via TCP using /dev/ in Linux

Small example below:

Now we starting listener on 8081 port:
nc -l 127.0.0.1 8081 &

We are going to send "1" to our listener:
echo 1 > /dev/tcp/127.0.0.1/8081
1 # We got it
[1]+  Done                    nc -l 127.0.0.1 8081