From the developer:
This mod enabled rendering of player’s body in first person view.
As a minecraft player who mostly plays on singleplayer, I wanted the first person view look better than it is now. The first person view only shows right arm and no matter how good the skin is, I can only see the right arm’s skin in first person mode. So I decided to enable rendering of the rest of the body in first person mode, making the game look more realistic and allowing the players to see front of the player’s model and skin in first person mode. This mod is unfinished and a work in progress.