Westinghouse 1B37 TR Cell (ATR cell) measuring 35x25mm.This has the serial number 248971 stamped and written on the base, and also the number 252337 marked on. Frequency range 8.5 to 9.0GHz, and up to 250kW peak power. This ATR Cell is used with the 1B24 TR Cell. See also 1B35A.