Pallet is used in organ terminology to describe the level, flap, door, stopper, whatever that opens and closes the flow of air to a pipe or set of pipes.  A pallet magnet is used in direct action windchests to close the holes that feed the pipes.  

Here's a collection of pallet magnets and stuff about them.

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Two pallet magnets

Here's a comparison of a Reisner 80Ω pallet magnet (left) and a Wicks 20Ω.

I modify pallet magnets to use as actuators for other electromechanical actions.  In this picture I've modified a pallet magnet by removing the valve stopper and attaching a metal lever to the front of it so it can lift things when its activated.

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Modified pallet magnet

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Horizontal action

Here's an example of a pallet magnet acting to lift a lever.