TJ (T@diz) rašė:
> Wikipedia :)
> Rain resistance is measured as a hydrostatic head in millimetres (mm). 
> This indicates the pressure of water needed to penetrate a fabric. Heavy 
> or wind-driven rain has a higher pressure than light rain. Standing on a 
> groundsheet increases the pressure on any water underneath. Fabric with 
> a hydrostatic head rating of 1000 mm or less is best regarded as shower 
> resistant, with 1500 mm being usually suitable for summer camping. Tents 
> for year-round use generally have at least 2000 mm; expedition tents 
> intended for extreme conditions are often rated at 3000 mm. Where 
> quoted, groundsheets may be rated for 5000 mm or more.
> 
> 
kuo daugiau mm , tuo labiau dušna joje miegot.
Jei nemiegi toj palapinėj savaitę laiko po lietum, nereikia kreipt 
dėmėsio į tuos mm.