This model is based on the Clone Wars phase 2 helmet design. It is scaled to fit a human head about 23.5" round; however, some scaling may be required. The file is designed with the backplate removable so it can be taken on and off easily. I recommend using magnets and elastics to keep the backplate in place. There is only 1 file for the filter, but you need to print this twice as it is on both sides of the mask. There is a version of the Base with and without the lense depending on what you are trying to print. So be careful and make sure you pick the right file.