The filter bag is the part of the Voltera 105 that does the actual work. Water is drawn in, passes through the mesh and flows out again at the back, while leaves, sand and fine sediment stay behind in the bag.
This is an original Kokido bag. It consists of a fine-mesh section that the water runs through and a dark fabric base with a drawstring, so the dirt you have collected can be let out from underneath instead of turning the whole bag inside out. The two black caps at the top attach the bag to the unit.
Kokido supplies bags for the Voltera 105 in several mesh grades, from coarse for leaves to fine for sand and dust. Before you order, check the manual of your own Voltera 105 to see which type is fitted now, so you get the bag that matches the dirt you are lifting out of your pool.
Worth keeping one in reserve for the start of the swimming season. A torn or worn bag is replaced in moments, and that costs a great deal less than a new unit.