Hamilton Buhl Schoolmate personal stereo/mono headphone features foam ear cushions, 1/8" plug, 1/4" adaptor stereo/mono. Headphone can be used with all school audio equipment and is ideal for all ages/grades. Foam ear cushions, replaceable. Headphones can be used with virtually all school audio equipment. Speaker drivers: 30 mm cobalt magnet. Frequency response: 20 Hz -20 kHz. 1/8" plug, 1/4" adaptor stereo/mono. Cord length: 9''. Impedance: 32 ohms. No switches to set or special plug adapters to change the headphone automatically adjusts for a stereo or mono system. Headphones come in heavy-duty, write-on, reclosable bag. Compatible with iPods /iTouches/MP3 players, iPhones/cell phones, CD players/stereos, TVs, most gaming systems, cassette players, record players. Dimensions: 6"(H) x 2"(W) x 6"(D). Weight: 0. 16 lbs. 1 year warranty. Never worry about mismatching headphones between different sources and damaging ears or equipment. No switches to set or special plug adapters to change - the headphone knows if it is plugged into a stereo or mono system and automatically adjusts. Operates in 1/8 inch stereo, 1/8 inch mono, 1/4 inch stereo or 1/4 inch mono modes. SchoolMate personal mono/stereo headphone is designed and built to withstand the rigors of classroom use while providing high quality sound.