The Holman Professional Rain Gauge Cylinder measures rainfall in millimetres over a set period, usually 24 hours. The outer housing collects excess rain up to 250mm in total until measured separately in the calibrated tube. When the measuring tube is full, additional rain overflows into the outer cylinder. Pour the rainwater from the outer cylinder into the measuring tube, and you read the amount of rain you have received. Get accurate readings from the 1mm increments measurements. Supplied with stainless steel screws and rainfall chart. Made from UV-stabilised materials. The top of the gauge or funnel, has a larger surface area than the top of the measuring cylinder.