@Override
    public void onUpdate(ItemStack stack, World world,
            Entity ent, int par4, boolean par5) {
        if (!stack.hasTagCompound()) {
            stack.setTagCompound(new NBTTagCompound());
        }

        if (!stack.getTagCompound().hasKey("SubItemName")) {
            switch (stack.getItemDamage()) {
                case 0:
                    stack.getTagCompound().setString("SubItemName", "kilo");
                case 1:
                    stack.getTagCompound().setString("SubItemName", "mega");
                case 2:
                    stack.getTagCompound().setString("SubItemName", "giga");
                case 3:
                    stack.getTagCompound().setString("SubItemName", "tera");
                default:
                    stack.getTagCompound().setString("SubItemName", "kilo");
            }
        }
    }