Compatible with all Linear access receivers & controllers</br>Quick-disconnect key ring</br>Factory programmed MegaCode format supports more than 1 million codes</br>Includes two 2016-type lithium batteries; Operating freq: 318MHz</br>Please refer the Installation Manual before use.</br></br>Product Description</br></br>Linear Act-31B Keychain Transmitter (1-Channel)</br><br/>http://www.amazon.com/gp/product/B000F5KF96