The present invention includes pure single-crystalline metal oxide and metal fluoride nanostructures, and methods of making same. According to one embodiment, the stackable dispenser comprises a first container comprising a substantially circular base portion defining a central opening. The rail charger charges multiple batteries at one time. The negative pressure provider can apply a negative pressure to the inside of the outer tube. For example, the tether element may have a diagonal orientation, or different tether elements may have different lengths. A blocking member is also concentrically mounted on the adjustment track or ring, which is in turn arranged without a relative sliding among them within the spool.