Wema Waste Senders Wema products of Norway are renowned for manufacturing high quality tank sender units for a variety of applications including fuel, fuel oil, water, grey water and black water. They are used extensively in marine, transport and recreational vehicles world wide and specified by many original equipment manufacturers. The Wema waste sender is produced in a standard USA resistance (240-33 Ohms) and is available in six standard lengths from 100 to 760mm. Custom lengths can be manufactured to specification for large quantities. The sender utilises Wema's innovative reed switch design which means there are no mechanical components to wear out. The only moving part is the float which travels vertically along the shaft. The sender is fitted with a removable screen making it easy to disassemble and clean if required.