An ordinary funnel-type raingauge has been in use for all manual measurements since the earliest days of observing. The design has varied over the years but today the Met Office strongly encourages conformity in order to maximise comparability of readings across the network. The standard design has a rim of diameter 5 in (127 mm) standing 12 in (30 cm) above the ground. Raingauges based on the standard design are adapted to meet specific needs; there is a version having a capacity to hold a large volume of rain which is used in remote sites where readings may only be taken once a month. Exposure of the gauge should be on open ground distant from the effects of sheltering objects. At a few windy sites, established a number of years ago, there may be a surrounding turf wall of diameter 3 m and height 30 cm which shields the gauge from the extreme effects of strong winds. Systematic differences as large as 12% have been noted between an unsheltered gauge and one within a turf wall. It is not the present practice to build turf walls at new stations.