GUI Sound would appear to be a Taiwan based designer and manufacturer of loudspeakers
OEM supplier for Polycom Soundpoint
Used in Model IP331 handsets
GUI Sound Loudspeaker
Designed for Telco subscriber equipment use
Part # UR52W4
Paper cone
47mm diameter - round
22mm height
Impedance is estimated to be in the range 6 - 8 Ohms (DC voice-coil resistance is 4 Ohms)
Being designed for Telco use, it would be fair to expect frequency response from around 250Hz to 6Khz (3dB points)
Judging by the size and intended application, this speaker would handle around 250mW comfortably
Comes complete with the mounting bracket
Very similar to the Stetron Telco loudspeaker we also have advertised
Non returnable unless found to be not as described