Hi guys,

What is the use of this screw?

I believe its a hex for changing the shaft for fitting different type of self locking props.

thank you, so how do i go about it? how to change adapter to allow other kind of props, since these are not easy to find in any shop.

You'll need to find self locking propeller ,
you can buy DJI 9443 PROPS, some clones are available for cheap.

https://www.quadkopters.com/product/propellers/dji-9443-props/

Self locking props are a little hard to find locally and even expensive at times, you can  post a TO BUY ad on the forum and get a potential seller

DJI 9443 or similar clones don't fit on this motor as the shaft screw length is a bit short for them and the screw is to attach the bell to the SS 3mm shaft inside the motor.

thanks yash,

so can we remove the bell without removing the C clip at bottom of motor? only buy unscrewing that screw and pull bell out?

Nope it's a pretty tight fit you cant take it out by simply removing the screw which is itself very difficult to remove too. You will have to take off the c-clip to remove the bell.