The bands fit a little looser than the originals for my DT 770's ear pads but despite that I don't hear any noticeable differences with the sound. The pads are firm. They will take some breaking in to. I've had them for over a month now and using them on an average about 4 hrs for 5 days of the week and they feel relatively the same. I'm thinking of buying another pair so when I wash these I don't have to wait for them to dry. I live in a tropical climate so it can get a bit warm.
I didn't use any special tools to change the pads. I picked some random objects from my house that I figured weren't sharp and wouldn't cause damages to the part that fits on the headset. Believe it or not I used the top of a coat rack to the slide it on.
I recorded myself changing the pads that were totally demolished. If this helped you can leave a like on my youtube channel.