The Firefly 300MCD21K is a single-button keychain transmitter engineered to work with Linear Multi-Code fixed-code radio systems operating at 300 MHz. Designed as a direct replacement or spare for Multi-Code 300 MHz receivers commonly found on gate operators and garage door openers, it provides simple, reliable access control for residential or light commercial applications. This compact remote is Multi-Code compatible and uses classic fixed-code technology, making it a practical upgrade for legacy installations that still rely on DIP-switch coding.
Programming is straightforward: open the remote and match its 10-position DIP switch pattern to the corresponding switch settings in your Multi-Code 300 MHz receiver. No software or special tools are required. Because it uses the Multi-Code 300 MHz format, the Firefly 300MCD21K is not compatible with rolling-code systems or other Linear formats such as MegaCode (318 MHz) or Security+ style transmitters. Use it to replace lost remotes, add additional users, or extend the convenience of your existing Linear Multi-Code setup with a durable, pocket-friendly key fob design.
How to Program a Firefly 300MCD21K Multi-Code Remote
1. Remove the screw from the back of the remote. Push the sides of the remote together long ways. This will create a gap in the remote to put your fingernail in to push the remote apart.
2. Locate the 10 switch code on the receiver or a working remote. Your garage or gate will have an external receiver that will have the 10 switch code in it. If you have a working remote it is usually easier to use the switches from the remote.
3. Move the switches in the new remote so they are in the same order as the receiver or working remote.
4. Press the remote. The garage or gate should operate. If the remote does not work then reverse all the switches.
To download the manufacturers instructions click here.