Squat Wedge Block: Doctor-Designed Pair of Adjustable, Non-Slip Slant Boards for Elevated Heel Squats, Deadlifts, and Calf Stretching - Physical Therapy Equipment for Strength Training

Squat Slant Boards if you want to spend money. 2.5 plates below the heels if you don't. Really you need to increase ankle flexibility, but that is hard to do and takes forever. With these slant boards I can go hamstring to calf and not but-wink or have any issues.