A miniature version of the usual rectangular panel mount rocker switch - I saw these on a USB hub (for switching off each port individually) and just had to get some in, they are, well, too cute for words.
SPST (Single Pole, Single Throw, aka On-Off)
The bezel is 15mm by 10.5mm, the rocker itself is a diminutive 6.3mm x 9.83mm
You will need a rectangular hole in your panel about 12x9mm, there are the typical springy tabs to lock it in with a push-fit.
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