I have the Parkside POFA 12 router and the battery is pretty weak on it. Will the 4ah battery fit into this product?
Yes, it will fit this router. It will fit a lot better than you might expect too. The 4ah battery should fit all of the products in the x12v range of power tools from parkside. They may not sit as flush and even as the smaller battery but since the battery is further away from the handle of this, you shouldn't have any trouble using the larger battery with the router.