This is a Lectrosonics R400a Dual Receiver for wireless mics. It operates in the Block 19 frequency range from 486-512 UHF.
It is compatible with Lectrosonics Digital Hybrid wireless mics as well as other brands like Shure and Sennheiser via user selectable compatibility modes. ***No transmitters are included.
It features both balanced XLR and unbalanced 1/4" connections. It requires antennas (not included). Two AC power adapters are included.
This would be great for a small PA set up like for events, weddings, graduations etc. Also great for bands that want to go wireless either for singers or instruments.