Headquarters Fighter Command Stores Reference No. F.R/39. Incredibly rare Filter Room Directional Plotting 'Counter' used to display important information relating to an enemy raid. When details of aircraft were received at Group Filter Room level, the information was interpreted on a map table. Arrow shaped counters like this were produced in seven colours. Manufactured in an early plastic, approximately 2.2cm / 7/8" long, yellow with the number '2' to obverse and 2 dots on the reverse. Filter Room plotting equipment is even rarer to find than that of Operations Rooms. Discovered at the Filter Room of RAF Watnall, Headquarters of 12 Group Fighter Command during WW2. We have literally a handful of such items, most of which we are keeping. Tip absent. Stock code M26518.