About this 3D model

This is a filter for an Israeli civilian gas mask I bought on Amazon. It's only officially meant as a prop, but it's effectiveness as an actual filter is determined by how well you seal it, and whatever you stick inside as filter media... The thread on **GasMaskFilter_Top.stl** is designed according to the NATO spec STANAG 4155. It's commonly referred to as "40mm NATO thread". _Update 2/11/2014_: added **NATO_STANAG_4155_40mm_Adapter_rev5.stl**, which is just the 40mm thread model.