Signia now offers rechargeable hearing aids with their Charge&Go line. The other two hearing aids — Pure 312, and Pure 13 — refer to battery size, from smallest to largest. A smaller battery size affects how long you can listen before replacing the battery, but also the size of the device. All Signia devices connect directly to iPhones, and can connect to Android phones and TVs with the optional connectors. And they are able to be programmed remotely, so Top Notch Hearing can easily customize your hearing experience.