8540.99.10 00 - - -Electron guns; Radio frequency (RF) interaction structures for microwave tubes of subheading 8540.71, 8540.72 or 8540.79 8540.99.90 00 - - -Other ###>TÉU, TPAC, TPMD, TPG, TM, TMÉU, TACI, TC, TCR: