maozhang.net
The other type of non-military headgear seen on Mao badges is the "hard-hat" made from woven strips of bamboo. The natural resilience of bamboo provided equivalent protection to aluminium or plastic, but with better ventilation. These hard-hats were widely worn by miners, forestry workers, and some construction workers.
50mm 12.6g
Ceramic
51mm 11.2g
Ceramic
69mm 23.2g
47mm 7.3g
PLA miners wearing bamboo hard-hats:
illustrations from a 1968 lianhuanhua entitled (approximately) The Victory Song of the Selfless Character