Please read the full description before placing your order and ask questions before buying. Please be aware that this is not "plug and play" item. Alignment needed such as heights, azimuth, and zenith, like any other heads even an original. Record level and bias also need to be performed on the deck. I would recommend to use 16 kHz alignment tape to adjust heads precisely. This listing is for two different replacement heads one recording and one playback (one of each) for Technics RS-1800 series or Otari MX series reel to reel tape deck. For 1/4" tape 2 track stereo reel-to-reel. Fits Technics models RS-1500, RS-1700, RS-1800. Also suitable for Otari 2 track stereo with 1/4" tape MX-5050BIII. Heads were made by the same company who made them for Otari in the late 90th. The original company who made them was out of business. Otari contacted another company to make heads. All late Otari MX-5050 were made with those heads. Please see the picture. Heads are new, prior to putting them for sale they were tested by JRF magnetics. John found them very close to the original and considered them the best replacement on the market. All technical characteristics are available upon request.