Mounted to the inside of the helmet shell, the system is extremely small and lightweight.

该系统非常小巧轻便，安装在头盔内侧。

youdao

Two types of the multilayered fibrous material in the form of high tenacity fiber helmet shell....

由两种类型的在多层纤维材料中的高韧性纤维形成的头盔壳体。

youdao

A safety helmet comprises a shell and a heat dissipating device.

一种安全帽，其包括：一个外壳和一个散热装置。

youdao

Presses with the force of several tons are required to cut through the material before pieces are draped, molded and steamed to form the helmet shell.

NPR: Pride and Production in a Vermont Helmet Factory

Riddell established the company in 1927, but it was not until 1939 that its first soft plastic-shell football helmet was released to the public.

FORBES: Why Football Helmet Manufacturer Riddell Should Be Very Concerned About Concussion Litigation