It is very durable because it is made nylon polymer which hold up to some abuse yet will not mar or damage wheels
The plunger on this tool is spring loaded so once installed will stay in place while mounting the tire, and you can adjust it with hands by little efforts.
This bead depressor pushes the bead down into the center of the wheel which helps mounting and demounting tires especially done well with low profile side walls and run flats.
A simple but must have tool when changing those hard to mount low profile, and run-flat tires.
Sliding bottom guide decreases stress on tool and tire