I've not really studied it but it seems to me that they do have an affect (for sand, forest, snow anyway) - but if they are working in places in addition to where they are supposed to I have not checked.
They really need to be tested thoroughly.
I've not really studied it but it seems to me that they do have an affect (for sand, forest, snow anyway) - but if they are working in places in addition to where they are supposed to I have not checked.
They really need to be tested thoroughly.
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