MFJ-281 ClearTone speakers are designed to restore the smooth sound of sine waves that CW naturally generates and makes it easy to copy and bring out communication speech fidelity that you never knew existed. They were carefully designed to improve the intelligibility of speech in the frequency range of 600 to 4,000 Hz, while reducing undesirable noise, static, and hum. The MFJ 281 ClearTone speakers feature a top-grade 3 in. Mylar cone mounted in a well-designed speaker baffle. They are covered with a fine mesh metal grille that allows sound to radiate without being muffled. The included versatile swivel mounting brackets let you direct sound where you want it.