Bricker - Part LEGO - 193au Minifig, Headgear Helmet Old with Thin Chinstrap - Visor Dimple Presence Undetermined
BrickLink - Part 50665 : LEGO Minifigure, Headgear Helmet Space / Town with Thick Chin Strap - with Visor Dimples (Reissue with Top Dimple) [Minifigure, Headgear] - BrickLink Reference Catalog