public boolean onTickInGame(float f, Minecraft minecraft)
{
    if (minecraft.thePlayer.inventory.armorItemInSlot(1) != null)
    {
        ItemStack itemstack = minecraft.thePlayer.inventory.armorItemInSlot(1);
        if (itemstack.itemID == 1005)
        {
        EntityPlayer.setPotionEffect(Potion.invisibility, 30);
        }
    }
    return true;
}