The Smith seated calf raise targets the soleus, the deep calf muscle that works hardest when the knee is bent. Sitting on a bench under the Smith machine bar with the balls of your feet on a block, you raise and lower your heels against the load resting on your thighs. Because the bar path is fixed, you can focus purely on the stretch and squeeze.
Log your smith seated calf raise sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.