I started using these on fresh strings, the top ones sounded good, but the lower ones sounded really bad, so bad that I thought the guitar was broken on the bass side. I turns out that these picks are quite flexible, but they are too long, so I trimmed them and now they sound quite well. I honestly don’t know if you are supposed to trim them to taste.
I have heat teated them to fit into my thumb, since mine are kinda bigish, they take it well. I heavily recommend it because you can mold it to your finger.
They are quite expensive at ~10 bucks for a non-divisible pack of four, I love the ultex picks because they are hard and on the brighter side, so I bit the bullet.
I might probably still buy them again, if they are still manufactured.