Figure 1.

The in house fabricated Si₃N₄ window storage box. This box has the same outer diameter as most standard cryo‐TEM grid boxes (shown in the far right as a comparison) and fits most cryodevices such as FEI Vitrobot plunge freezer, Instec cryostorage mounting block, and Bionanoprobe sample transferring system. The box at the left has eight storage positions, whereas the box at the right has four storage positions. The window storage box is made of aluminium to minimize possible contamination from other high Z metals. It can be enclosed with a transparent lid secured by a stainless steel screw in the middle. The storage box allows windows to be vertically placed with predetermined orientation and to prevent fragile membranes from touching the aluminium wall during long‐term storage and sample transportation.