Энэ нь Presentation Таны хэл дээр байхгүй байгаа, Нь харах: English (en),
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Presented By: Roland Bunch

Event: ECHO East Africa Highlands Symposium 2014 (2014-10-27)

A-frame levels can be used to trace contour lines for soil conservation, or irrigation ditches at ½ % slope. They are highly accurate, and cost nothing.