Sing your heart out with this Singing Machine SMM-107 unidirectional dynamic microphone, which works with standard Singing Machine karaoke systems and comes with a VHF receiver for easy wireless connectivity. Compatible with standard Singing Machine karaoke systems, For use with your existing device. Note: you can only use 1 wireless microphone per machine, as more than 1 receiver will cause interference VHF receiver: Provides a wide frequency response and high sensitivity  Number of Batteries: 4 Number of Settings: 1 Battery Type: Alkaline Measurements: 13 Height/Inches, 2.2 Length/Inches, 6.5 Width/Inches Assembly: Assembled Base Material: 90% Plastic, 5% Metal, 5% Other 5% Or Less Battery Size: Aaa Care: Wipe Clean Country of Origin: Imported