My squat form was horrible before using these. My heels were always up and my depth was never deep enough. When I started using these it became easier to keep my heels planted. My depth was at about a 45 degree angle before, and now I can get to 90 degrees and under. My squat has increase about 20 pounds more than expected in a month. Overall, very useful product.
I do like these in practice and the design is a really great concept. My only critique is that they should come in different slopes. I purchased two pairs and I stack them, which works fine but is just a bit on the high side--whereas one pair is too shallow a slope for my needs. Overall, I recommend this product and they are my preferred method for adding a squat wedge to my workouts.