Received my slant blocks a few weeks ago and have been using them to help my mobility with squats and split squats. Really liking the slant blocks, and loving the eco-friendly cork! They are also non-slip, which great. Can't speak to the durability yet, but so far no issues with the quality. I like that they are small and light enough to pick up and store when not in use in my basement home gym.
I've found the slant blocks to be a very useful addition to my training. The non-slip cork surface is light and durable. I highly recommend them for anyone struggling with getting squat depth due to limited ankle mobility. They also double up as a good calf stretching block. The fact that they are stackable and can be positioned at varying widths and angles makes them a lot more versatile than slant boards.
The slant blocks are great for squats and calf raises. You'll appreciate the cork material especially when you're sweating, you won't lose your grip.
They are a nice addition to the sole mate. I highly recommend both, they have helped me with my recovery from plantar fasciitis.