In the past few years, we have covered plenty of calf stretchers here. The StrongTek Cork Slant Board Set is also worth a look. It comes with everything you need to stretch your lower leg muscles. These are made of high density cork. They have a detachable design, so you can try 4 degrees (8.5°, 17°, 25.5°, 34°).
This calf stretcher has a lightweight design, so you can easily take it with you anywhere. It can withstand up to 480lbs of weight. You can find out more about it here.