There is resin, but it is close to hard rubber (impression that opened immediately after purchase).
Doubt about durability.
Remove from 1 plastic bag, leave it outside for 10 months (sunlight, rain leaves).
When it is pressed with nails it cracks.
Also close the mouth of the plastic bag for 10 months and keep the remaining one kept in the box
I also cracked when I pressed it with the nail.
Even if I left it outdoors, it kept the same quality even if it was kept.