This Draper 20M Water Level is ideal for blind, room to room measurements & for checking gradients over long distances. The hose is filled with water & the level is found when both graduations chosen are the same. The kit comprises of 20m (approx.) length of PVC hose that is graded in 0.5 & single centimetre graduations, a funnel, colouring crystals, water stop plugs & marker rings.