Mini Slide Switch : 3-Pin, SPDT, 0.3A (3-Pack) Pololu 1408
These small single-pole, double-throw (SPDT) slide switches are rated for 300 mA at 50 VDC and have a 0.1″ pin spacing that works with standard solderless breadboards.
Used alone, they make great on/off power switches for low power electronics or offer a convenient way to switch between two analog or digital input signals. The switch can also be combined with a MOSFET to make a higher-power switch (see our Mini MOSFET Slide Switch with Reverse Voltage Protection for an example using a smaller, surface-mount slide switch).
They are sold in packs of 3, so ordering one of this product gets you three switches.
