D-Cut Shaft Collar with Threaded Holes, ID 25mm x OD 42mm, 12mm Long, Carbon Steel S45C (Electroless Nickel Plating), SC2512MTN
SGD $23.85
Set collars have an internal set screw that is marred onto the shaft to lock it in place. It is fastened with an allen key, making the locking process quick and easy.