Pair of RF Field Strength Meters (handheld). Virtually identical. Used to help Planning and Installation staff working around Rowridge short wave transmitter to deal with faults as well as helping to identify areas where high RF electromagnetic levels existed by allowing them to take spot readings as the go about their business on that site. This item is marked for use at 56.75 MC/s (Mhz) which was one of the frequencies in being transmitted from that site at the time. It was produced by the Aerial Section of BBC Research department, and possibly dates from the 1960s. Very good examples of the type of equipment R&D used to produce from scratch for very particular BBC use at a particular location.