QUANTIFOIL® with square holes and relatively narrow bars can be used in electron microscopy to support a thin carbon film, which by itself is too fragile to span a grid square. The QUANTIFOIL® types with square holes constitute an optimum between a maximum of open area on the one hand, and mechanical stability on the other hand.
The table below gives an overview of the available QUANTIFOIL® types with square holes.
| QUANTIFOIL® type | Hole size in µm | Spacing in µm | Period in µm |
| S 7/2 | 7 | 2.0 | 9 |
| S 35/5 | 35 | 5 | 40 |
| S 35/10 | 35 | 10 | 45 |
