• Open the darkroom bag or use a changing tent to load the film holder in complete darkness.
• Pick up the empty film holder and locate the dark slide.
• Slide the dark slide out of the holder and set it aside in a safe place.
• Take a sheet of 4x5 film and place it on a flat surface, emulsion side up.
• Lift the film by the edges and insert it into the film slot, emulsion side facing the lens.
• Slide the dark slide back into the holder.
• Repeat the process for the second sheet of film.
  
  You're now ready to insert the loaded film holder into your camera and start shooting!

A 4x5 film holder is typically around 3/8 inch (or 9.5 mm) thick. This measurement can vary slightly depending on the specific brand and model of the film holder, but most 4x5 film holders fall within this range. It's important to keep the thickness of the film holder in mind when using it with your camera, as it can affect the focus and positioning of your images.

4x5 format is considered a large format in photography. Large format cameras use sheet film (usually 4x5 inches or larger), which is loaded into individual film holders one sheet at a time. In contrast, medium format cameras typically use roll film (such as 120 or 220), which is loaded into a spool and can shoot multiple exposures before needing to be reloaded. So, while both 4x5 and medium format cameras produce high-quality images, they differ in their approach to film loading and the size of the film used.