Microphone
From Amazon
Chord | Replacement Beltback Transmitter For The NU4 | 864.8MHz | Red
HW Audio
Chord NU4 Beltpack Transmitter Yellow 863.1mhz NU4-BT863.1
Inta Audio
Replacement Beltpack Transmitter for Chord NU4 - Yellow 863.1MHz
Gear 4 Music
Chord NU4 Beltpack Transmitter, 863.1MHz, Yellow