Hard rubber with good grip. It loses elasticity, so the potholes are a bit more jarring, but it is very durable.

The tire is fine, definitely harder than the one with the umbrella but much more durable. Basically, it's incomprehensible!! Now, as for the installation, it is a bit difficult but anyone can do it on their own... I needed three screwdrivers... Just use your knee or one leg, no need for cyclists or special craftsmen... Do it yourself, it's easy.

The first impression is quite good.. Definitely harder than the corresponding ones with an interior. It will show over time how durable they are.
Now, as for the installation, I found it easier than the regular ones with an interior. However, it requires 2 people for the installation. I soaked them in hot water for about 15-20 minutes. Then, I placed it on one side of the rim, holding and pressing with both hands while the second person used 2 screwdrivers to place them under the tire and pull against the rim. I also used a little WD40 and they went in perfectly. Minus 1 star for the long delivery time (20 days for Cyprus)... if possible.