The Geemarc i-Loop Hands-Free Neckloop is ideal for hard of hearing individuals with T-coil hearing aids who want to the optimum listening experience from their audio devices. It's a helpful accessory that transforms the sound coming from an audio device into an acoustic field compatible with hearing aids set to the T position. Compatible with iPods and other MP3 players, audio and CD players, PC's, etc. Fits almost any device that would accept ear buds or headphones. Connects to the 3.5 mm jack of the audio source. This neckloop is lightweight and comfortable to wear - it weighs less than 3-1/2 oz. with batteries installed. Measures 2-3/4 x 1-3/8. Uses 2 AAA batteries, not included. 1-year warranty.