The 221A from ACST GmbH is a Frequency Multiplier with Input Frequency 375 to 550 GHz, Output Frequency 750 to 1100 GHz, Input Power 2 to 10 mW, Output Power -10 dBm, Frequnecy 375 to 550 GHz. Tags: Waveguide, Waveguide Multiplier. More details for 221A can be seen below.