| 摘要 |
The unit in question is a self-supporting, tottaly combustible unit for use against frosts. Said unit consists of a solid combustible body having at least one passage passing through same longitudinally and open at both ends thereof. The solid body consists of a mixture of combustible materials. The lower end of said body is provided with at least one air inlet channel in communication with the above mentioned passage and extending up to the sidewalls of the aforesaid body.
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