We designed the Arras Tapestry Loom so you could choose your preferred way to warp. Nylon clips can hold the warp sett rod on top of the top beam (to warp from the front) or at the back of the top beam (to warp from the back).
If you always warp from the same side of the loom, you don't need both sets of clips. You do need one clip at each end of the warp sett rod.