This is an airbrush, compressor, or other airbrush related accessories for modeling use.
Mr. Airbrush Holder lives up to his name: holding airbrushes! Created specifically to fit Gunze's Mr. Linear Compressors L5 and L7. (Well, okay, he lives up to his name most of the time; he can't hold the PS290 Procon Boy LWA Trigger airbrush due to that airbrush's eccentric shape. That's all right, Mr. Airbrush Holder, we still love you...)