KeySonic ACK-540 RF+. Device interface: RF Wireless, Recommended usage: HTPC, Keyboard form factor: Mini. Frequency band: 2.4 GHz, Wireless range: 10 m. Wireless receiver interface: USB. Keyboard dimensions (WxDxH): 291 x 197 x 29 mm, Keyboard weight: 657 g, Receiver dimensions (WxDxH): 63 x 11.5 x 23 mm. Power source type: Battery, Battery type: AAA