As mentioned upthread. They were initially designed as an emergency break-away system if something were to get stuck in the front guard, but they can also be fitted at the rear.
The loop of the stay is a push fit into the clip, so can be popped out to pull the mudguard away from the frame to make wheel removal easier.
https://www.sjscycles.co.uk/mudguards/sks-secu-clip-30mm-each/
As mentioned upthread. They were initially designed as an emergency break-away system if something were to get stuck in the front guard, but they can also be fitted at the rear.
The loop of the stay is a push fit into the clip, so can be popped out to pull the mudguard away from the frame to make wheel removal easier.