Many models of filtering half-masks have 2-panel or 3-panel design for compactness and user-friendliness. This half-mask fits easily into the pocket of working suit, does not take much space, does not cause discomfort during use.
2-panel design is usually used for easy half-masks. One of the main advantages — compact size.
3-panel design is used for more complex models, many users refer to them as the most comfortable as 3-panel half-mask repeats mimic facial movements and is suitable for different face types.