The Leslie "half-moon" switch is classic means of controlling a Leslie speaker.
Since LeslieHookupKits were sold as add-ons, Leslie needed to design a switch in a housing which could easily be attached to organs in a convenient location. The result was the half-moon switch.
See also MainEnsembleEchoSwitch and ChorusTremoloSwitch.
The switch housings are made of bakelite, and therefore somewhat brittle. If you leave the switch attached to the front rail of your organ while moving it, _you will break it_ on a door frame, sooner or later.
If you do break your switch, HalfmoonElectronics is now manufacturing replacement parts.
Some recommend mounting your half-moon switch(es) with velcro so that they are easy to remove for transport, and so that it is possible to reposition the switches to suit the preference of the player.
Trek sells rocker switches neatly mounted in replacement ?CheekBlocks which can be used to control your Leslie.
The modern LeslieHookupKits from HammondSuzuki come with ugly metal boxes with toggle switches on them. However, HammondSuzuki now makes a new version of the half-moon switch as well (with a nice wood body, even.)
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