The compact Transmitter Solutions MultiCode-compatible Firefly 300MCD21K garage door or gate opener remote control transmitter from Garage Door Supply Company is a mini keychain remote with 10 binary (two-position) switches. These switches allow you to choose from more than 1,000 coding options. This one-button 300MHz remote will control one garage door or gate operator. A keychain and 12-volt battery is included. It's just 1 7/8 in. x 1 1/2 in. x 1/2 in. in size.The Transmitter Solutions Firefly model 300MCD21K remote can replace your Linear MultiCode 3060 and other Linear MultiCode 300 MHz remotes, and works with Linear MultiCode receivers. It's also compatible with Chamberlain 300MC and Keystone Heddolf M220 remote controls. Or, use it to replace any of these Transmitter Soluti8ons models: 300MCD21K, 300MCD21V, 300MCD22K, 300MCD22V, EMP300MCD21V or FFII300MCD21K.Product Highlights: