Linear

The Model DXT-41 1-Button, 1-Channel Key Ring Transmitter is a battery powered, portable, miniature transmitter designed for use with Linear`s DX Format receivers. Each transmitter can be used in a limitless number of wireless remote control applications...

The Model DXR-701 is a digital receiver with an isolated relay output designed for use with Linear products. More Specifications (PDF File) Transmitter sold separate, Click Here