After 4 years, one cracked last week. The other is fine. They were like ~$1 from the orient delivered to my door. Unsure if to be happy or to suspect they were not silicone or mixed with rubber. Replaced the cracked one today with spare silicone one, back to normal.
Perhaps I expected them to be eternal... So next I want clear silicone ones to erase the doubt of the black ones. Anyone has a source ?
The US vendors want to wring the wallet to the extreme for 20+ times the price.